From 1073af21305360bd33903c533cdac57e9f936294 Mon Sep 17 00:00:00 2001
From: Yuuta Liang <yuutaw@student.cs.ubc.ca>
Date: Tue, 28 Nov 2023 18:19:39 -0800
Subject: Move TUI and GUI into separate packages

Signed-off-by: Yuuta Liang <yuutaw@student.cs.ubc.ca>
---
 src/main/ui/IssueDialog.java                    | 101 ----
 src/main/ui/IssueScreen.java                    | 167 ------
 src/main/ui/JCA.java                            | 219 --------
 src/main/ui/Main.java                           |   2 +
 src/main/ui/MainScreen.java                     | 233 --------
 src/main/ui/MainUI.java                         | 695 -----------------------
 src/main/ui/MgmtScreen.java                     | 152 ------
 src/main/ui/RevokeDialog.java                   | 184 -------
 src/main/ui/Screen.java                         |  31 --
 src/main/ui/TemplateEditDialog.java             |  73 ---
 src/main/ui/TemplateSetScreen.java              | 157 ------
 src/main/ui/TemplatesScreen.java                | 138 -----
 src/main/ui/UIHandler.java                      |  45 --
 src/main/ui/gui/IssueDialog.java                | 101 ++++
 src/main/ui/gui/MainUI.java                     | 696 ++++++++++++++++++++++++
 src/main/ui/gui/RevokeDialog.java               | 184 +++++++
 src/main/ui/gui/TemplateEditDialog.java         |  73 +++
 src/main/ui/gui/widgets/CertEditDialog.java     | 108 ++++
 src/main/ui/gui/widgets/CertTableModel.java     | 129 +++++
 src/main/ui/gui/widgets/GCBuilder.java          | 213 ++++++++
 src/main/ui/gui/widgets/LogTableModel.java      |  79 +++
 src/main/ui/gui/widgets/QRPanel.java            |  77 +++
 src/main/ui/gui/widgets/TemplateTableModel.java | 105 ++++
 src/main/ui/gui/widgets/UIUtils.java            | 168 ++++++
 src/main/ui/tui/IssueScreen.java                | 168 ++++++
 src/main/ui/tui/JCA.java                        | 220 ++++++++
 src/main/ui/tui/MainScreen.java                 | 234 ++++++++
 src/main/ui/tui/MgmtScreen.java                 | 153 ++++++
 src/main/ui/tui/Screen.java                     |  31 ++
 src/main/ui/tui/TemplateSetScreen.java          | 157 ++++++
 src/main/ui/tui/TemplatesScreen.java            | 138 +++++
 src/main/ui/tui/UIHandler.java                  |  45 ++
 src/main/ui/widgets/CertEditDialog.java         | 108 ----
 src/main/ui/widgets/CertTableModel.java         | 129 -----
 src/main/ui/widgets/GCBuilder.java              | 213 --------
 src/main/ui/widgets/LogTableModel.java          |  79 ---
 src/main/ui/widgets/QRPanel.java                |  77 ---
 src/main/ui/widgets/TemplateTableModel.java     | 105 ----
 src/main/ui/widgets/UIUtils.java                | 168 ------
 39 files changed, 3081 insertions(+), 3074 deletions(-)
 delete mode 100644 src/main/ui/IssueDialog.java
 delete mode 100644 src/main/ui/IssueScreen.java
 delete mode 100644 src/main/ui/JCA.java
 delete mode 100644 src/main/ui/MainScreen.java
 delete mode 100644 src/main/ui/MainUI.java
 delete mode 100644 src/main/ui/MgmtScreen.java
 delete mode 100644 src/main/ui/RevokeDialog.java
 delete mode 100644 src/main/ui/Screen.java
 delete mode 100644 src/main/ui/TemplateEditDialog.java
 delete mode 100644 src/main/ui/TemplateSetScreen.java
 delete mode 100644 src/main/ui/TemplatesScreen.java
 delete mode 100644 src/main/ui/UIHandler.java
 create mode 100644 src/main/ui/gui/IssueDialog.java
 create mode 100644 src/main/ui/gui/MainUI.java
 create mode 100644 src/main/ui/gui/RevokeDialog.java
 create mode 100644 src/main/ui/gui/TemplateEditDialog.java
 create mode 100644 src/main/ui/gui/widgets/CertEditDialog.java
 create mode 100644 src/main/ui/gui/widgets/CertTableModel.java
 create mode 100644 src/main/ui/gui/widgets/GCBuilder.java
 create mode 100644 src/main/ui/gui/widgets/LogTableModel.java
 create mode 100644 src/main/ui/gui/widgets/QRPanel.java
 create mode 100644 src/main/ui/gui/widgets/TemplateTableModel.java
 create mode 100644 src/main/ui/gui/widgets/UIUtils.java
 create mode 100644 src/main/ui/tui/IssueScreen.java
 create mode 100644 src/main/ui/tui/JCA.java
 create mode 100644 src/main/ui/tui/MainScreen.java
 create mode 100644 src/main/ui/tui/MgmtScreen.java
 create mode 100644 src/main/ui/tui/Screen.java
 create mode 100644 src/main/ui/tui/TemplateSetScreen.java
 create mode 100644 src/main/ui/tui/TemplatesScreen.java
 create mode 100644 src/main/ui/tui/UIHandler.java
 delete mode 100644 src/main/ui/widgets/CertEditDialog.java
 delete mode 100644 src/main/ui/widgets/CertTableModel.java
 delete mode 100644 src/main/ui/widgets/GCBuilder.java
 delete mode 100644 src/main/ui/widgets/LogTableModel.java
 delete mode 100644 src/main/ui/widgets/QRPanel.java
 delete mode 100644 src/main/ui/widgets/TemplateTableModel.java
 delete mode 100644 src/main/ui/widgets/UIUtils.java

diff --git a/src/main/ui/IssueDialog.java b/src/main/ui/IssueDialog.java
deleted file mode 100644
index c757d8f..0000000
--- a/src/main/ui/IssueDialog.java
+++ /dev/null
@@ -1,101 +0,0 @@
-package ui;
-
-import model.asn1.exceptions.ParseException;
-import model.ca.Template;
-import model.csr.CertificationRequest;
-import model.x501.Name;
-import ui.widgets.CertEditDialog;
-
-import javax.swing.*;
-import java.awt.event.ActionEvent;
-import java.util.List;
-
-import static ui.widgets.UIUtils.alert;
-
-/**
- * Dialog that allows user to choose a template and edit the incoming CSR properties to get it signed.
- */
-public class IssueDialog extends CertEditDialog<Template> {
-    /**
-     * The list of templates.
-     */
-    private final List<Template> templates;
-
-    /**
-     * The incoming CSR.
-     */
-    private final CertificationRequest csr;
-
-    /**
-     * Combo box to choose template.
-     */
-    private JComboBox<String> componentTemp;
-
-    /**
-     * The selected template, immutable.
-     */
-    private Template selectedTemplate;
-
-    /**
-     * EFFECTS: Init the dialog with CSR and templates.
-     * REQUIRES: csr must have a subject; templates must have at least one enabled.
-     */
-    public IssueDialog(CertificationRequest csr, List<Template> templates) {
-        super();
-        this.csr = csr;
-        this.templates = templates;
-
-        setTitle("Issue new certificate");
-        buttonOK.setText("Issue");
-        componentTemp.setModel(new DefaultComboBoxModel<>(templates.stream()
-                .filter(Template::isEnabled).map(Template::getName).toArray(String[]::new)));
-        componentTemp.addActionListener(this::onTemplateChange);
-
-        onTemplateChange(null);
-        pack();
-    }
-
-    /**
-     * EFFECTS: Create the templates combo box.
-     * MODIFIES: this
-     */
-    @Override
-    protected JComponent createTemplateComponent() {
-        return componentTemp = new JComboBox<>();
-    }
-
-    /**
-     * EFFECTS: Validate the form, compose a resulting template, close the dialog.
-     * MODIFIES: this
-     */
-    @Override
-    protected void onOK(ActionEvent ev) {
-        if (textFieldSubject.getText().isEmpty()) {
-            alert(this, getTitle(), "Subject must not be empty.");
-            return;
-        }
-        try {
-            res = new Template(selectedTemplate.getName(),
-                    true,
-                    Name.parseString(textFieldSubject.getText()),
-                    ((SpinnerNumberModel) spinnerValidity.getModel()).getNumber().longValue());
-            dispose();
-        } catch (ParseException e) {
-            alert(this, getTitle(), e);
-        }
-    }
-
-    /**
-     * EFFECTS: Handle template change, rewrite the form with the new template.
-     * MODIFIES: this
-     */
-    private void onTemplateChange(ActionEvent ae) {
-        selectedTemplate = templates.stream()
-                .filter(temp -> temp.getName().equals(componentTemp.getSelectedItem()))
-                .findFirst()
-                .get();
-        textFieldSubject.setText(selectedTemplate.getSubject() != null ? selectedTemplate.getSubject().toString() :
-                csr.getCertificationRequestInfo().getSubject().toString());
-        spinnerValidity.setValue(selectedTemplate.getValidity());
-    }
-}
diff --git a/src/main/ui/IssueScreen.java b/src/main/ui/IssueScreen.java
deleted file mode 100644
index 3e70a0a..0000000
--- a/src/main/ui/IssueScreen.java
+++ /dev/null
@@ -1,167 +0,0 @@
-package ui;
-
-import model.asn1.exceptions.ParseException;
-import model.ca.Template;
-import model.csr.CertificationRequest;
-import model.pki.cert.Certificate;
-import model.x501.Name;
-
-/**
- * The screen that accepts a CSR and template and allows user to change its properties and issue.
- */
-public class IssueScreen implements UIHandler {
-    private final JCA session;
-
-    private Template template;
-    private CertificationRequest incomingCSR;
-
-    /**
-     * EFFECTS: Init with the session.
-     */
-    public IssueScreen(JCA session) {
-        this.session = session;
-    }
-
-    /**
-     * EFFECTS: Set current template and CSR in use by args.
-     * REQUIRES: args.length = 2, args[0] instanceof CertificateRequest, args[1] instanceof Template
-     * MODIFIES: args[1]
-     */
-    @Override
-    public void enter(Object... args) {
-        this.incomingCSR = (CertificationRequest) args[0];
-        this.template = (Template) args[1];
-    }
-
-    /**
-     * EFFECTS: Print help.
-     */
-    @Override
-    public void help() {
-        System.out.print("show\tView the current certificate\n"
-                + "set\tSet properties or template\n"
-                + "commit\tIssue the certificate\n"
-                + "exit\tDiscard and go to main menu\n"
-                + "help\tPrint this message\n");
-    }
-
-    /**
-     * EFFECTS: Print pending cert info.
-     */
-    @Override
-    public void show() {
-        System.out.println("Requested Subject:\t" + incomingCSR.getCertificationRequestInfo().getSubject());
-        System.out.println("Subject:\t" + (template.getSubject() == null
-                ? incomingCSR.getCertificationRequestInfo().getSubject()
-                : template.getSubject()));
-        System.out.println("Template:\t" + template.getName());
-        System.out.println("Validity:\t" + template.getValidity() + " days");
-    }
-
-    /**
-     * EFFECTS: Issue the cert and log it.
-     * MODIFIES: session
-     */
-    @Override
-    public void commit() {
-        try {
-            Certificate certificate = session.getCa().signCert(incomingCSR.getCertificationRequestInfo(), template);
-            session.save();
-            System.out.println(Utils.toPEM(certificate.encodeDER(), "CERTIFICATE"));
-            session.setScreen(Screen.MAIN);
-        } catch (Throwable e) {
-            System.out.println(e.getMessage());
-        }
-    }
-
-    /**
-     * EFFECTS: Set or unset the subject.
-     * MODIFIES: this
-     */
-    private void handleIssueSetSubject(String val) {
-        try {
-            if (val == null) {
-                template = new Template(template.getName(), template.isEnabled(), (Name) null, template.getValidity());
-            } else {
-                template = new Template(template.getName(), template.isEnabled(), val, template.getValidity());
-            }
-        } catch (ParseException e) {
-            System.out.println(e.getMessage());
-        }
-    }
-
-    /**
-     * EFFECTS: Set or unset the validity.
-     * MODIFIES: this
-     */
-    private void handleIssueSetValidity(String val) {
-        if (val == null) {
-            System.out.println("Cannot unset validity");
-            return;
-        }
-        try {
-            long i = Long.parseLong(val);
-            if (i <= 0) {
-                System.out.println("Invalid validity days");
-                return;
-            }
-            template = new Template(template.getName(), template.isEnabled(), template.getSubject(), i);
-        } catch (NumberFormatException ignored) {
-            System.out.println("Invalid validity days");
-        }
-    }
-
-    /**
-     * EFFECTS: Handle the set command.
-     * MODIFIES: this
-     */
-    private void handleIssueSet(String... args) {
-        if (args.length != 2 && args.length != 3) {
-            System.out.println("Usage: set <key> <value>");
-            System.out.println("Supported keys: subject validity");
-            return;
-        }
-        String val = args.length == 3 ? args[2] : null;
-        switch (args[1]) {
-            case "subject":
-                handleIssueSetSubject(val);
-                break;
-            case "validity":
-                handleIssueSetValidity(val);
-                break;
-            default:
-                System.out.println("Unknown key");
-                break;
-        }
-    }
-
-    @Override
-    public void command(String... args) {
-        if (args[0].equals("set")) {
-            handleIssueSet(args);
-        } else {
-            help();
-        }
-    }
-
-    /**
-     * EFFECTS: Clear the certificates and return main.
-     * MODIFIES: this
-     */
-    @Override
-    public Screen exit() {
-        incomingCSR = null;
-        template = null;
-        return Screen.MAIN;
-    }
-
-    /**
-     * EFFECTS: Return "/subj/ %"
-     */
-    @Override
-    public String getPS1() {
-        return String.format("/%s/ %%", template.getSubject() == null
-                ? incomingCSR.getCertificationRequestInfo().getSubject()
-                : template.getSubject());
-    }
-}
diff --git a/src/main/ui/JCA.java b/src/main/ui/JCA.java
deleted file mode 100644
index 64cfaa3..0000000
--- a/src/main/ui/JCA.java
+++ /dev/null
@@ -1,219 +0,0 @@
-package ui;
-
-import model.asn1.exceptions.InvalidDBException;
-import model.asn1.exceptions.ParseException;
-import model.ca.CertificationAuthority;
-import persistence.Decoder;
-import persistence.FS;
-
-import java.io.IOException;
-import java.nio.charset.StandardCharsets;
-import java.nio.file.Path;
-import java.security.NoSuchAlgorithmException;
-import java.security.spec.InvalidKeySpecException;
-import java.util.Scanner;
-
-/**
- * Main program
- */
-public class JCA {
-    /**
-     * Default db file (./data/ca.json)
-     */
-    private static final Path PATH_DEFAULT = Path.of("data", "ca.json");
-
-    /**
-     * Instances of the five screens;
-     */
-    private final UIHandler mainScreen;
-    private final UIHandler mgmtScreen;
-    private final UIHandler issueScreen;
-    private final UIHandler templatesScreen;
-    private final UIHandler templateSetScreen;
-    /**
-     * The CA
-     */
-    private CertificationAuthority ca;
-    /**
-     * The current screen.
-     */
-    private UIHandler screen;
-
-    /**
-     * There are unsaved changes.
-     */
-    private boolean unsaved = false;
-
-    /**
-     * EFFECTS: Init with main screen and empty CA. No private key and no CA cert.
-     * Throws {@link NoSuchAlgorithmException} when crypto issue happens.
-     */
-    public JCA() throws NoSuchAlgorithmException, InvalidKeySpecException {
-        this.mainScreen = new MainScreen(this);
-        this.mgmtScreen = new MgmtScreen(this);
-        this.issueScreen = new IssueScreen(this);
-        this.templatesScreen = new TemplatesScreen(this);
-        this.templateSetScreen = new TemplateSetScreen(this);
-
-        setScreen(Screen.MAIN);
-
-        this.ca = new CertificationAuthority();
-    }
-
-    /**
-     * EFFECT: Checks if the CA is installed or not (according to the desired state) and print if not matching. Returns
-     * true if matching.
-     */
-    public boolean checkCA(boolean requireInstalled) {
-        if (requireInstalled && ca.getCertificate() == null) {
-            System.out.println("No CA installed");
-            return false;
-        } else if (!requireInstalled && ca.getCertificate() != null) {
-            System.out.println("CA already installed");
-            return false;
-        }
-        return true;
-    }
-
-    /**
-     * EFFECTS: Read PEM from stdin, matched the given tag.
-     * Throws {@link ParseException} if the input is incorrect.
-     */
-    public Byte[] handleInputPEM(String desiredTag) throws ParseException {
-        final Scanner scanner = new Scanner(System.in);
-        StringBuilder in = new StringBuilder();
-        while (true) {
-            final String line = scanner.nextLine();
-            in.append(line);
-            in.append("\n");
-            if (line.matches("-----END .*-----")) {
-                break;
-            }
-        }
-        return Utils.parsePEM(Utils.byteToByte(in.toString().getBytes(StandardCharsets.UTF_8)), desiredTag);
-    }
-
-    /**
-     * EFFECT: Set the current screen with optional args. Exit the program when mode is null.
-     * MODIFIES: this
-     */
-    public void setScreen(Screen mode, Object... args) {
-        if (mode == null) {
-            System.exit(0);
-        }
-        switch (mode) {
-            case MAIN:
-                this.screen = mainScreen;
-                break;
-            case MGMT:
-                this.screen = mgmtScreen;
-                break;
-            case ISSUE:
-                this.screen = issueScreen;
-                break;
-            case TEMPLATES:
-                this.screen = templatesScreen;
-                break;
-            case TEMPLATE_SET:
-                this.screen = templateSetScreen;
-                break;
-        }
-        screen.enter(args);
-    }
-
-    /**
-     * EFFECTS: Read the database file and replace all local states.
-     * MODIFIES: this
-     */
-    private void load() {
-        if (unsaved) {
-            System.out.println("Current database is not saved yet.");
-            return;
-        }
-        try {
-            this.ca = Decoder.decodeCA(FS.read(PATH_DEFAULT));
-        } catch (InvalidDBException | NoSuchAlgorithmException e) {
-            System.out.println(e.getMessage());
-            if (e.getCause() != null) {
-                System.out.println(e.getCause().getMessage());
-                e.getCause().printStackTrace();
-            }
-        }
-    }
-
-    /**
-     * EFFECTS: Handle input line
-     * MODIFIES: this
-     */
-    private void handleLine(String... args) {
-        if (args[0].equals("log")) {
-            ca.getLogs().forEach(System.out::println);
-            return;
-        }
-        if ("help".equals(args[0])) {
-            screen.help();
-            System.out.println("log\tView audit logs");
-            System.out.println("load\tLoad database");
-            System.out.println("save\tSave database");
-        } else if ("commit".equals(args[0])) {
-            screen.commit();
-        } else if ("show".equals(args[0])) {
-            screen.show();
-        } else if ("exit".equals(args[0])) {
-            setScreen(screen.exit());
-        } else if ("save".equals(args[0])) {
-            save();
-        } else if ("load".equals(args[0])) {
-            load();
-        } else {
-            screen.command(args);
-        }
-        printPS1();
-    }
-
-    /**
-     * EFFECTS: Print the '*user@JCA PS1' line
-     */
-    private void printPS1() {
-        System.out.printf("%s%s@JCA %s ",
-                unsaved ? "*" : "",
-                ca.getUser(),
-                screen.getPS1());
-    }
-
-    /**
-     * EFFECTS: Save the DB
-     */
-    public void save() {
-        try {
-            FS.write(PATH_DEFAULT, Decoder.encodeCA(ca));
-            unsaved = false;
-        } catch (IOException e) {
-            System.out.println(e.getMessage());
-        }
-    }
-
-    /**
-     * EFFECTS: Run the program
-     */
-    public void run() {
-        printPS1();
-        final Scanner scanner = new Scanner(System.in);
-        while (true) {
-            String[] args = scanner.nextLine().split(" ");
-            if (args.length <= 0 || args[0].isBlank()) {
-                printPS1();
-                continue;
-            }
-            handleLine(args);
-        }
-    }
-
-    public void setUnsaved(boolean unsaved) {
-        this.unsaved = unsaved;
-    }
-
-    public CertificationAuthority getCa() {
-        return ca;
-    }
-}
diff --git a/src/main/ui/Main.java b/src/main/ui/Main.java
index 4dbcea1..918a06c 100644
--- a/src/main/ui/Main.java
+++ b/src/main/ui/Main.java
@@ -2,6 +2,8 @@ package ui;
 
 import com.formdev.flatlaf.FlatIntelliJLaf;
 import model.EventLog;
+import ui.gui.MainUI;
+import ui.tui.JCA;
 
 import javax.swing.*;
 import java.awt.event.WindowAdapter;
diff --git a/src/main/ui/MainScreen.java b/src/main/ui/MainScreen.java
deleted file mode 100644
index 8a85881..0000000
--- a/src/main/ui/MainScreen.java
+++ /dev/null
@@ -1,233 +0,0 @@
-package ui;
-
-import model.asn1.ASN1Object;
-import model.asn1.UtcTime;
-import model.asn1.exceptions.ParseException;
-import model.asn1.parsing.BytesReader;
-import model.ca.Template;
-import model.csr.CertificationRequest;
-import model.pki.cert.Certificate;
-import model.pki.crl.CertificateList;
-import model.pki.crl.Reason;
-import model.pki.crl.RevokedCertificate;
-
-import java.io.File;
-import java.io.FileOutputStream;
-import java.io.IOException;
-import java.io.OutputStream;
-import java.time.ZoneId;
-import java.time.ZonedDateTime;
-import java.util.Optional;
-
-/**
- * The main screen that handles submenus (mgmt / issue / template), list certs, revoke certs, generate CRLs.
- */
-public class MainScreen implements UIHandler {
-    private final JCA session;
-
-    /**
-     * EFFECTS: Init with the parent session.
-     */
-    public MainScreen(JCA session) {
-        this.session = session;
-    }
-
-    /**
-     * EFFECTS: Print help
-     */
-    @Override
-    public void help() {
-        System.out.print("mgmt\tView and manage the CA certificate\n"
-                + "issue\tIssue a certificate\n"
-                + "show\tList all issued certificates\n"
-                + "export\tExport a certificate to file (DER)\n"
-                + "template\tManage templates\n"
-                + "revoke\tRevoke a certificate\n"
-                + "crl\t\tSign CRL\n"
-                + "log\t\tView audit logs\n"
-                + "exit\tExit\n"
-                + "help\tPrint this message\n");
-    }
-
-    /**
-     * EFFECTS: Print each issued cert in Subject Serial Status format.
-     */
-    @Override
-    public void show() {
-        session.getCa().getSigned().forEach(cert -> {
-            System.out.printf("%s\t%d\t%s\n",
-                    cert.getCertificate().getSubject().toString(),
-                    cert.getCertificate().getSerialNumber().getLong(),
-                    session.getCa().getRevoked().stream().anyMatch(rev -> rev.getSerialNumber().getLong()
-                            == cert.getCertificate().getSerialNumber().getLong()) ? "REVOKED" : "OK");
-        });
-    }
-
-    /**
-     * EFFECTS: Read the input CSR.
-     */
-    private CertificationRequest handleIssueInputCSR() {
-        try {
-            return new CertificationRequest(new BytesReader(session.handleInputPEM("CERTIFICATE REQUEST")),
-                    false);
-        } catch (ParseException e) {
-            System.out.println(e.getMessage());
-            return null;
-        }
-    }
-
-    /**
-     * EFFECTS: Handle the issue command. Read CSR, find template, switch to issue screen.
-     */
-    private void handleIssue(String... args) {
-        if (!session.checkCA(true)) {
-            return;
-        }
-        if (args.length <= 1) {
-            System.out.println("Usage: issue <template>");
-            return;
-        }
-        Template tmp = session.getCa().findTemplate(args[1], true);
-        if (tmp == null) {
-            System.out.println("Cannot find the template specified");
-            return;
-        }
-        CertificationRequest req = handleIssueInputCSR();
-        if (req != null) {
-            session.setScreen(Screen.ISSUE, req, new Template(tmp.getName(),
-                    true,
-                    tmp.getSubject(),
-                    tmp.getValidity()));
-        }
-    }
-
-    /**
-     * EFFECTS: Find issued and not revoked certificate by serial. Return null if not found.
-     */
-    private Certificate findCertBySerial(int serial) {
-        Optional<Certificate> c = session.getCa().getSigned()
-                .stream()
-                .filter(cert -> cert.getCertificate().getSerialNumber().getLong() == serial)
-                .findFirst();
-        if (c.isEmpty()) {
-            System.out.println("Cannot find the certificate specified");
-            return null;
-        }
-        if (session.getCa().getRevoked().stream().anyMatch(rev -> rev.getSerialNumber().getLong() == serial)) {
-            System.out.println("The certificate has already been revoked.");
-            return null;
-        }
-        return c.get();
-    }
-
-    /**
-     * EFFECTS: Handle the revoke command and log it.
-     * MODIFIES: session
-     */
-    private void handleRevoke(String... args) {
-        if (args.length < 3) {
-            System.out.println("Usage: revoke <serial> <reason>");
-            return;
-        }
-        try {
-            final Reason reason = Reason.valueOf(args[2]);
-            int serial = Integer.parseInt(args[1]);
-            Certificate c = findCertBySerial(serial);
-            if (c == null) {
-                return;
-            }
-            session.getCa().revoke(new RevokedCertificate(ASN1Object.TAG_SEQUENCE, null,
-                    c.getCertificate().getSerialNumber(),
-                    new UtcTime(UtcTime.TAG, null, ZonedDateTime.now(ZoneId.of("UTC"))), reason));
-            session.save();
-        } catch (IllegalArgumentException ignored) {
-            System.out.println("Illegal serial number or reason");
-        }
-    }
-
-    /**
-     * EFFECTS: Export a cert to file
-     */
-    private void handleExport(String... args) {
-        if (args.length < 3) {
-            System.out.println("Usage: export <serial> <path>");
-            return;
-        }
-        try {
-            int serial = Integer.parseInt(args[1]);
-            Certificate c = findCertBySerial(serial);
-            if (c == null) {
-                return;
-            }
-            final File fd = new File(args[2]);
-            final OutputStream out = new FileOutputStream(fd);
-            out.write(Utils.byteToByte(c.encodeDER()));
-            out.close();
-        } catch (IllegalArgumentException ignored) {
-            System.out.println("Illegal serial number");
-        } catch (IOException e) {
-            System.out.println(e.getMessage());
-        }
-    }
-
-    /**
-     * EFFECTS: Issue a CRL and do audit log.
-     * MODIFIES: session
-     */
-    private void handleCRL() {
-        if (!session.checkCA(true)) {
-            return;
-        }
-        try {
-            CertificateList crl = session.getCa().signCRL();
-            session.save();
-            System.out.println(Utils.toPEM(crl.encodeDER(), "X509 CRL"));
-        } catch (Throwable e) {
-            System.out.println(e.getMessage());
-        }
-    }
-
-    /**
-     * EFFECTS: Handle commands
-     */
-    @Override
-    public void command(String... args) {
-        switch (args[0]) {
-            case "mgmt":
-                session.setScreen(Screen.MGMT);
-                return;
-            case "issue":
-                handleIssue(args);
-                return;
-            case "revoke":
-                handleRevoke(args);
-                return;
-            case "export":
-                handleExport(args);
-                return;
-            case "template":
-                session.setScreen(Screen.TEMPLATES);
-                return;
-            case "crl":
-                handleCRL();
-                return;
-        }
-        help();
-    }
-
-    /**
-     * EFFECTS: Exit the program
-     */
-    @Override
-    public Screen exit() {
-        return null;
-    }
-
-    /**
-     * EFFECTS: return "/ %"
-     */
-    @Override
-    public String getPS1() {
-        return "/ %";
-    }
-}
diff --git a/src/main/ui/MainUI.java b/src/main/ui/MainUI.java
deleted file mode 100644
index 34cc224..0000000
--- a/src/main/ui/MainUI.java
+++ /dev/null
@@ -1,695 +0,0 @@
-package ui;
-
-import model.GroupObserver;
-import model.ObservedData;
-import model.Observer;
-import model.asn1.exceptions.InvalidCAException;
-import model.asn1.exceptions.InvalidDBException;
-import model.asn1.exceptions.ParseException;
-import model.asn1.parsing.BytesReader;
-import model.ca.AuditLogEntry;
-import model.ca.CertificationAuthority;
-import model.ca.Template;
-import model.csr.CertificationRequest;
-import model.pki.cert.Certificate;
-import model.pki.crl.CertificateList;
-import model.pki.crl.RevokedCertificate;
-import persistence.Decoder;
-import persistence.FS;
-import ui.widgets.*;
-
-import javax.swing.*;
-import javax.swing.event.ChangeEvent;
-import java.awt.*;
-import java.awt.event.ActionEvent;
-import java.io.IOException;
-import java.io.OutputStream;
-import java.nio.file.Files;
-import java.nio.file.Path;
-import java.nio.file.StandardOpenOption;
-import java.security.InvalidKeyException;
-import java.security.NoSuchAlgorithmException;
-import java.security.SignatureException;
-import java.security.interfaces.RSAPublicKey;
-
-import static java.awt.GridBagConstraints.*;
-import static ui.widgets.UIUtils.*;
-
-/**
- * The main GUI.
- * +------------------------------++------------------------------++------------------------------+
- * |  JCA                       X ||  JCA                       X ||  JCA                       X |
- * +------------------------------++------------------------------++------------------------------+
- * |Load Save                  CSR||Load Save   Sign Revoke Export||Load Save      New Ena Dis Del|
- * +----+-------+-----------+-----++----+-------+----------+------++----+-------+-----------------+
- * | CA | Certs | Templates |     || CA | Certs | Templates|      || CA | Certs | Templates       |
- * +----+-------+-----------+-----++-+--+-----+-+----+-----+------++-+--+---+---+-----+-----------+
- * | Welcome to JCA               || | Serial | Subj | Bef | To   || | Name | Subj    |  Validity |
- * |                              |+-+--------+------+-----+------++-+------+---------+-----------+
- * | Private key:    Generate     ||      (Issued Certs)          ||      (All Templates)         |
- * | CA certificate: Install CSR  ||                              ||                              |
- * +------------------------------++------------------------------++------------------------------+
- * +-----+----------+-------------++-----+----------+-------------++-----+----------+-------------+
- * |Time | Operator | Action      ||Time | Operator | Action      ||Time | Operator | Action      |
- * +-----+----------+-------------++-----+----------+-------------++-----+----------+-------------+
- * |  (Audit Logs)                ||  (Audit Logs)                ||  (Audit Logs)                |
- * +------------------------------++------------------------------++------------------------------+
- * | Ready: (Last operation)      || Unsaved: (Last operation)    || Ready: (Last Operation)      |
- * +------------------------------++------------------------------++------------------------------+
- */
-public class MainUI extends JFrame {
-    /**
-     * Default db file (./data/ca.json)
-     */
-    private static final Path PATH_DEFAULT = Path.of("data", "ca.json");
-
-    /**
-     * The root panel (Box layout).
-     */
-    private final JPanel rootPanel = new JPanel(new BoxLayout(rootPane, BoxLayout.PAGE_AXIS));
-
-    /**
-     * Common toolbar buttons
-     */
-    private final JButton buttonToolbarLoad = btn("Load", "open.png", this::onLoad);
-    private final JButton buttonToolbarSave = btn("Save", "saveall.png", this::onSave);
-
-    /**
-     * Toolbar that switches with the tab.
-     */
-    private final JPanel panelContextAwareToolbar = new JPanel(new CardLayout(0, 0));
-
-    /**
-     * Tab root.
-     */
-    private final JTabbedPane tabbedPane = new JTabbedPane();
-
-    /**
-     * CA tab
-     */
-    private final JLabel labelCACertificate = new JLabel();
-    private final JLabel labelPrivateKey = new JLabel();
-    private final JButton buttonGenPrivKey = btn("Generate", 'G', this::onGeneratePrivateKey);
-    private final JButton buttonInstallCA = btn("Install", 'I', this::onInstallCA);
-    private final JButton buttonGenCSR = btn("CSR", this::onSignCSR);
-    private final QRPanel panelQR = new QRPanel(256);
-    private final JToolBar toolbarCA = new JToolBar();
-    private final JButton buttonCAToolbarCRL = btn("CRL", "publisher.png", this::onCRL);
-
-    /**
-     * Certs tab
-     */
-    private JPanel panelCertsTab;
-    private final JTable tableCerts = new JTable();
-    private final CertTableModel modelCerts = new CertTableModel();
-    private final JToolBar toolbarCerts = new JToolBar();
-    private final JButton buttonCertsToolbarNew = btn("Sign", "new.png", this::onIssue);
-    private final JButton buttonCertsToolbarRevoke = btn("Revoke", "deletetest.png", this::onRevokeCert);
-    private final JButton buttonCertsToolbarExport = btn("Export", "export.png", this::onExportCert);
-
-    /**
-     * Templates tab
-     */
-    private JPanel panelTmpTab;
-    private final JTable tableTemplates = new JTable();
-    private final TemplateTableModel modelTemplates = new TemplateTableModel();
-    private final JToolBar toolbarTemplates = new JToolBar();
-    private final JButton buttonTemplatesToolbarNew = btn("New", "new.png", this::onNewTemplate);
-    private final JButton buttonTemplatesToolbarEnable = btn("Enable", "enable.png", this::onEnableTemplate);
-    private final JButton buttonTemplatesToolbarDisable = btn("Disable", "disable.png", this::onDisableTemplate);
-    private final JButton buttonTemplatesToolbarDelete = btn("Delete", "deletetest.png", this::onDeleteTemplate);
-
-    /**
-     * Logs region
-     */
-    private final JPanel panelLogs;
-    private final JTable tableAuditLogs = new JTable();
-    private final LogTableModel modelAuditLogs = new LogTableModel();
-
-    /**
-     * Status region
-     */
-    private final JLabel labelStatus = new JLabel();
-    private ObservedData<Boolean> unsaved = new ObservedData<>(false, this::acceptUnsaved);
-
-    /**
-     * CA and observers
-     */
-    private CertificationAuthority ca;
-
-    private final GroupObserver obs = new GroupObserver();
-
-    /**
-     * EFFECTS: Setup the CA and GUI.
-     */
-    public MainUI() {
-        setTitle("JCA");
-        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
-
-        setContentPane(rootPanel);
-        rootPanel.setLayout(new BoxLayout(rootPanel, BoxLayout.PAGE_AXIS));
-
-        rootPanel.add(setupToolbar());
-        final JSplitPane splitPane = new JSplitPane(0);
-        rootPanel.add(splitPane);
-        splitPane.setLeftComponent(setupTabs());
-        rootPanel.getRootPane().setDefaultButton(buttonGenPrivKey);
-
-        splitPane.setRightComponent(panelLogs = defView(scrTbl(tableAuditLogs), "No audit logs"));
-        panelLogs.setPreferredSize(new Dimension(panelLogs.getPreferredSize().width,
-                panelLogs.getPreferredSize().height / 2));
-        panelLogs.setBackground(new Color(-1));
-
-        rootPanel.add(labelStatus);
-        labelStatus.setBorder(BorderFactory.createEmptyBorder(4, 8, 8, 8));
-
-        ca = new CertificationAuthority();
-
-        tableAuditLogs.setModel(modelAuditLogs);
-        tableCerts.setModel(modelCerts);
-        tableTemplates.setModel(modelTemplates);
-
-        tabbedPane.addChangeListener(this::onChangeTab);
-        setupObservers();
-
-        setCA(ca);
-    }
-
-    // -----BEGIN HELPER METHODS-----
-
-    /**
-     * EFFECTS: Rewind the CA and refresh all pages.
-     * MODIFIES: ca (observer), this
-     */
-    private void setCA(CertificationAuthority ca) {
-        this.ca = ca;
-        ca.registerObserver(obs);
-
-        modelAuditLogs.setPtrData(ca.getLogs());
-        modelCerts.setPtrData(ca.getSigned());
-        modelCerts.setPtrRevokedData(ca.getRevoked());
-        modelTemplates.setPtrData(ca.getTemplates());
-
-        renderRefresh();
-    }
-
-    /**
-     * EFFECTS: Set the QR code data to either null (no public key) or PEM-encoded PKCS#1 public key.
-     */
-    private void renderQRPublicKey() {
-        if (ca.getPublicKey() == null) {
-            panelQR.setData(null);
-            return;
-        }
-        panelQR.setData(Utils.toPEM(Utils.byteToByte(ca.getPublicKey().getEncoded()), "PUBLIC KEY"));
-    }
-
-    // -----END HELPER METHODS-----
-
-    // -----BEGIN DATA OBSERVERS-----
-
-    /**
-     * EFFECTS: Setup observers
-     * MODIFIES: this
-     */
-    private void setupObservers() {
-        obs.register(AuditLogEntry.class, this::acceptAuditLog);
-        obs.register(Certificate.class, this::acceptCertificate);
-        obs.register(RSAPublicKey.class, this::acceptPrivateKey);
-        obs.register(Template.class, this::acceptTemplate);
-    }
-
-    /**
-     * EFFECTS: Handle new audit log, hide default text, notify the model
-     * MODIFIES: this
-     * REQUIRES: direction == ADD, i >= 0
-     */
-    private void acceptAuditLog(AuditLogEntry auditLogEntry, int direction, int i) {
-        setContentVisible(panelLogs, true);
-        modelAuditLogs.fireTableRowsInserted(ca.getLogs().size() - 1, ca.getLogs().size() - 1);
-        acceptUnsaved(unsaved.get(), Observer.DIRECTION_CHANGE, Observer.INDEX_NOT_IN_LIST);
-    }
-
-    /**
-     * EFFECTS: Handle CA cert or new issued cert, notify CA page or model accordingly, hide certs default text
-     * MODIFIES: this
-     * REQUIRES: direction == CHANGE or ADD, i >= 0 or -1
-     */
-    private void acceptCertificate(Certificate cert, int direction, int i) {
-        if (i == Observer.INDEX_NOT_IN_LIST) {
-            renderCAPage();
-        } else {
-            setContentVisible(panelCertsTab, true);
-            modelCerts.fireTableRowsInserted(i, i);
-        }
-    }
-
-    /**
-     * EFFECTS: Handle added, changed, or deleted template; notify model, show / hide default text.
-     * MODIFIES: this
-     * REQUIRES: i >= 0.
-     */
-    private void acceptTemplate(Template template, int direction, int i) {
-        setContentVisible(panelTmpTab, !ca.getTemplates().isEmpty());
-        switch (direction) {
-            case Observer.DIRECTION_ADD:
-                modelTemplates.fireTableRowsInserted(i, i);
-                break;
-            case Observer.DIRECTION_CHANGE:
-                modelTemplates.fireTableRowsUpdated(i, i);
-                break;
-            case Observer.DIRECTION_REMOVE:
-                modelTemplates.fireTableRowsDeleted(i, i);
-                break;
-        }
-    }
-
-    /**
-     * EFFECTS: Handle added private key. Change buttons / labels accordingly.
-     * MODIFIES: this
-     */
-    private void acceptPrivateKey(RSAPublicKey pubKey, int direction, int i) {
-        renderCAPage();
-    }
-
-    /**
-     * EFFECTS: Handle status label change, set status to unsaved / saved + latest action.
-     * MODIFIES: this
-     */
-    private void acceptUnsaved(Boolean unsaved, int direction, int i) {
-        labelStatus.setText(unsaved ? "Unsaved" : "Ready");
-        if (!ca.getLogs().isEmpty()) {
-            labelStatus.setText(labelStatus.getText() + ": " + ca.getLogs().get(ca.getLogs().size() - 1).getAction());
-        }
-    }
-
-    // -----END DATA OBSERVERS----
-
-    // -----BEGIN RENDERERS-----
-
-    /**
-     * EFFECTS: Setup the toolbar.
-     * MODIFIES: this
-     */
-    private JToolBar setupToolbar() {
-        final JToolBar toolBar = new JToolBar();
-        toolBar.setAlignmentX(Component.LEFT_ALIGNMENT);
-        toolBar.setBorder(BorderFactory.createEmptyBorder(4, 8, 4, 8));
-
-        toolBar.add(buttonToolbarLoad);
-        toolBar.add(buttonToolbarSave);
-
-        toolBar.add(panelContextAwareToolbar);
-
-        panelContextAwareToolbar.add(toolbarTemplates, "CardToolbarTemplates");
-
-        toolbarTemplates.add(Box.createHorizontalGlue());
-        toolbarTemplates.add(buttonTemplatesToolbarNew);
-        toolbarTemplates.add(buttonTemplatesToolbarEnable);
-        toolbarTemplates.add(buttonTemplatesToolbarDisable);
-        toolbarTemplates.add(buttonTemplatesToolbarDelete);
-
-        panelContextAwareToolbar.add(toolbarCerts, "CardToolbarCerts");
-        toolbarCerts.add(Box.createHorizontalGlue());
-        toolbarCerts.add(buttonCertsToolbarNew);
-        toolbarCerts.add(buttonCertsToolbarRevoke);
-        toolbarCerts.add(buttonCertsToolbarExport);
-
-        panelContextAwareToolbar.add(toolbarCA, "CardToolbarCA");
-        toolbarCA.add(Box.createHorizontalGlue());
-        toolbarCA.add(buttonCAToolbarCRL);
-        return toolBar;
-    }
-
-    /**
-     * EFFECTS: Setup the tabs
-     * MODIFIES: this
-     */
-    private JTabbedPane setupTabs() {
-        tabbedPane.setAlignmentX(Component.LEFT_ALIGNMENT);
-        tabbedPane.setBorder(BorderFactory.createEmptyBorder(8, 8, 4, 8));
-
-        final JPanel panelTabCA = new JPanel();
-        panelTabCA.setLayout(new GridBagLayout());
-        tabbedPane.addTab("CA", panelTabCA);
-
-        panelTabCA.add(new JLabel("Welcome to JCA"), new GCBuilder().anchor(WEST).insectTop(8).build());
-        panelTabCA.add(labelPrivateKey, new GCBuilder().gridY(1).anchor(WEST).build());
-        panelTabCA.add(labelCACertificate, new GCBuilder().gridY(2).anchor(WEST).build());
-        panelTabCA.add(buttonGenPrivKey, new GCBuilder().gridXY(1, 1).fill(HORIZONTAL).build());
-        panelTabCA.add(buttonInstallCA, new GCBuilder().gridXY(1, 2).fill(HORIZONTAL).build());
-        panelTabCA.add(buttonGenCSR, new GCBuilder().gridXY(2, 2).fill(HORIZONTAL).build());
-        panelTabCA.add(panelQR, new GCBuilder().gridY(3).fill(HORIZONTAL).build());
-        panelTabCA.add(new JPanel(), new GCBuilder().gridXY(4, 4).expandXY().fill(BOTH).build());
-        tabbedPane.addTab("Certs", panelCertsTab = defView(scrTbl(tableCerts), "No issued certs"));
-        tabbedPane.addTab("Templates", panelTmpTab = defView(scrTbl(tableTemplates), "No templates"));
-
-        return tabbedPane;
-    }
-
-    /**
-     * EFFECTS: Render public key and CA to the CA page and toolbar
-     * MODIFIES: this
-     */
-    private void renderCAPage() {
-        renderQRPublicKey();
-        if (ca.getPublicKey() == null) {
-            labelPrivateKey.setText("Private key not installed");
-        } else {
-            labelPrivateKey.setText(String.format("%s key: %s ...",
-                    ca.getPublicKey().getAlgorithm(),
-                    ca.getPublicKey().getModulus().toString(16).substring(0, 16)));
-        }
-        if (ca.getCertificate() == null) {
-            labelCACertificate.setText("CA certificate not installed");
-        } else {
-            labelCACertificate.setText(String.format("<html>CA: %s<br>Issued by: %s</html>",
-                    ca.getCertificate().getCertificate().getSubject().toString(),
-                    ca.getCertificate().getCertificate().getIssuer().toString()));
-        }
-        buttonGenPrivKey.setEnabled(ca.getPublicKey() == null);
-        buttonInstallCA.setEnabled(ca.getPublicKey() != null && ca.getCertificate() == null);
-        buttonGenCSR.setEnabled(ca.getPublicKey() != null && ca.getCertificate() == null);
-        buttonCertsToolbarNew.setEnabled(ca.getPublicKey() != null && ca.getCertificate() != null);
-        buttonCAToolbarCRL.setEnabled(ca.getPublicKey() != null && ca.getCertificate() != null);
-    }
-
-    /**
-     * EFFECTS: Reset all GUI to initial state and render the CA again.
-     * MODIFIES: this
-     */
-    private void renderRefresh() {
-        acceptUnsaved(false, Observer.DIRECTION_CHANGE, Observer.INDEX_NOT_IN_LIST);
-        onChangeTab(null);
-        renderCAPage();
-
-        modelAuditLogs.fireTableDataChanged();
-        setContentVisible(panelLogs, !ca.getLogs().isEmpty());
-
-        modelCerts.fireTableDataChanged();
-        setContentVisible(panelCertsTab, !ca.getSigned().isEmpty());
-
-        modelTemplates.fireTableDataChanged();
-        setContentVisible(panelTmpTab, !ca.getTemplates().isEmpty());
-    }
-
-    // -----END RENDERERS-----
-
-    // -----BEGIN ACTION LISTENERS-----
-
-    /**
-     * EFFECTS: Switch toolbar according to tab change.
-     * MODIFIES: this
-     */
-    private void onChangeTab(ChangeEvent ev) {
-        final CardLayout toolbarCardLayout = (CardLayout) panelContextAwareToolbar.getLayout();
-        switch (tabbedPane.getSelectedIndex()) {
-            case 0: {
-                toolbarCerts.setEnabled(false);
-                toolbarTemplates.setEnabled(false);
-                toolbarCardLayout.show(panelContextAwareToolbar, "CardToolbarCA");
-                break;
-            }
-            case 1: {
-                toolbarCerts.setEnabled(true);
-                toolbarTemplates.setEnabled(false);
-                toolbarCardLayout.show(panelContextAwareToolbar, "CardToolbarCerts");
-                break;
-            }
-            case 2: {
-                toolbarCerts.setEnabled(false);
-                toolbarTemplates.setEnabled(true);
-                toolbarCardLayout.show(panelContextAwareToolbar, "CardToolbarTemplates");
-                break;
-            }
-        }
-    }
-
-    /**
-     * EFFECTS: Generate private key.
-     * MODIFIES: this
-     * REQUIRES: No private key / CA is installed.
-     */
-    private void onGeneratePrivateKey(ActionEvent ev) {
-        try {
-            ca.generateKey();
-            unsaved.set(true);
-        } catch (NoSuchAlgorithmException e) {
-            alert(rootPanel, "Generate private key", e);
-        } finally {
-            renderCAPage();
-        }
-    }
-
-    /**
-     * EFFECTS: Sign a CSR and save to disk (in binary form).
-     * MODIFIES: this
-     * REQUIRES: Proper private key installed, no CA.
-     */
-    private void onSignCSR(ActionEvent ev) {
-        final Path p = chooseFile(rootPanel, "DER binary (*.csr)", "csr");
-        if (p == null) {
-            return;
-        }
-
-        try {
-            final OutputStream fd = Files.newOutputStream(p,
-                    StandardOpenOption.WRITE,
-                    StandardOpenOption.TRUNCATE_EXISTING,
-                    StandardOpenOption.CREATE);
-            final CertificationRequest csr = ca.signCSR();
-            fd.write(Utils.byteToByte(csr.encodeDER()));
-            fd.close();
-            unsaved.set(true);
-        } catch (IOException | ParseException | NoSuchAlgorithmException | SignatureException | InvalidKeyException e) {
-            alert(rootPanel, "Sign certification request", e);
-        }
-    }
-
-    /**
-     * EFFECTS: Pick a certificate and install.
-     * MODIFIES: this
-     * REQUIRES: Proper private key is installed, no CA.
-     */
-    private void onInstallCA(ActionEvent ev) {
-        final Path p = chooseFile(rootPanel, "DER X.509 certificate (*.crt, *.pem)", "crt", "pem");
-        if (p == null) {
-            return;
-        }
-
-        try {
-            final Certificate crt = new Certificate(new BytesReader(UIUtils.openDERorPEM(p, "CERTIFICATE")),
-                    false);
-            ca.installCertificate(crt);
-            unsaved.set(true);
-        } catch (IOException | ParseException | InvalidCAException e) {
-            alert(rootPanel, "Install CA", e);
-        } finally {
-            renderCAPage();
-        }
-    }
-
-    /**
-     * EFFECTS: Load the database and refresh.
-     * MODIFIES: this
-     */
-    private void onLoad(ActionEvent ev) {
-        if (unsaved.get()) {
-            alert(rootPanel, "Load database from filesystem",
-                    "Unable to load: current modifications are not saved.");
-            return;
-        }
-
-        try {
-            setCA(Decoder.decodeCA(FS.read(PATH_DEFAULT)));
-        } catch (NoSuchAlgorithmException | InvalidDBException e) {
-            alert(rootPanel, "Load database from filesystem", e);
-        }
-    }
-
-    /**
-     * EFFECTS: Save database.
-     * MODIFIES: this
-     */
-    private void onSave(ActionEvent ev) {
-        try {
-            FS.write(PATH_DEFAULT, Decoder.encodeCA(this.ca));
-            unsaved.set(false);
-        } catch (IOException e) {
-            alert(rootPanel, "Save database to filesystem", e);
-        }
-    }
-
-    /**
-     * EFFECTS: Enable a template.
-     * MODIFIES: this
-     */
-    private void onEnableTemplate(ActionEvent ev) {
-        if (tableTemplates.getSelectedRow() == -1) {
-            return;
-        }
-
-        final Template t = ca.getTemplates().get(tableTemplates.getSelectedRow());
-        if (t.isEnabled()) {
-            return;
-        }
-        ca.setTemplateEnable(t, true);
-        unsaved.set(true);
-    }
-
-    /**
-     * EFFECTS: Disable a template.
-     * MODIFIES: this
-     */
-    private void onDisableTemplate(ActionEvent ev) {
-        if (tableTemplates.getSelectedRow() == -1) {
-            return;
-        }
-
-        final Template t = ca.getTemplates().get(tableTemplates.getSelectedRow());
-        if (!t.isEnabled()) {
-            return;
-        }
-        ca.setTemplateEnable(t, false);
-        unsaved.set(true);
-    }
-
-    /**
-     * EFFECTS: Delete a template.
-     * MODIFIES: this
-     */
-    private void onDeleteTemplate(ActionEvent ev) {
-        if (tableTemplates.getSelectedRow() == -1) {
-            return;
-        }
-
-        final Template t = ca.getTemplates().get(tableTemplates.getSelectedRow());
-        ca.removeTemplate(t);
-        unsaved.set(true);
-    }
-
-    /**
-     * EFFECTS: Save the selected cert as a DER binary.
-     * MODIFIES: this
-     */
-    private void onExportCert(ActionEvent ev) {
-        if (tableCerts.getSelectedRow() == -1) {
-            return;
-        }
-
-        final Certificate c = ca.getSigned().get(tableCerts.getSelectedRow());
-        final Path p = chooseFile(rootPanel, "DER binary (*.crt)", "crt");
-        if (p == null) {
-            return;
-        }
-        try {
-            final OutputStream fd = Files.newOutputStream(p,
-                    StandardOpenOption.WRITE, StandardOpenOption.TRUNCATE_EXISTING, StandardOpenOption.CREATE);
-            fd.write(Utils.byteToByte(c.encodeDER()));
-            fd.close();
-        } catch (IOException e) {
-            alert(rootPanel, "Export certificate", e);
-        }
-    }
-
-    /**
-     * EFFECTS: Show revocation dialog for the selected cert. Save enforced.
-     * MODIFIES: this
-     */
-    private void onRevokeCert(ActionEvent ev) {
-        if (tableCerts.getSelectedRow() == -1) {
-            return;
-        }
-
-        final Certificate c = ca.getSigned().get(tableCerts.getSelectedRow());
-        if (ca.getRevoked().stream().anyMatch(r ->
-                r.getSerialNumber().getLong() == c.getCertificate().getSerialNumber().getLong())) {
-            return;
-        }
-        final RevokeDialog diag = new RevokeDialog(c);
-        diag.pack();
-        diag.setLocationRelativeTo(this);
-        diag.setVisible(true);
-
-        final RevokedCertificate res = diag.getRes();
-        if (res == null) {
-            return;
-        }
-
-        ca.revoke(res);
-        onSave(null);
-    }
-
-    /**
-     * EFFECTS: Sign a CRL and save to disk. Save enforced.
-     * MODIFIES: this
-     * REQUIRES: Proper private key and CA cert installed.
-     */
-    private void onCRL(ActionEvent ev) {
-        final Path p = chooseFile(rootPanel, "DER CRL (*.crl)", "crl");
-        if (p == null) {
-            return;
-        }
-        try {
-            final OutputStream fd = Files.newOutputStream(p,
-                    StandardOpenOption.WRITE,
-                    StandardOpenOption.TRUNCATE_EXISTING,
-                    StandardOpenOption.CREATE);
-            final CertificateList crl = ca.signCRL();
-            fd.write(Utils.byteToByte(crl.encodeDER()));
-            fd.close();
-            onSave(null);
-        } catch (IOException | SignatureException | InvalidKeyException | NoSuchAlgorithmException e) {
-            alert(rootPanel, "Sign CRL", e);
-        }
-    }
-
-    /**
-     * EFFECTS: Pick a CSR, show issue dialog, sign cert. Save enforced.
-     * MODIFIES: this
-     * REQUIRES: Proper private key / CA is installed.
-     */
-    private void onIssue(ActionEvent ev) {
-        if (ca.getTemplates().stream().noneMatch(Template::isEnabled)) {
-            alert(rootPanel, "Issue new certificate", "No enabled templates.");
-            return;
-        }
-        final Path p = chooseFile(rootPanel, "DER CSR (*.csr, *.pem)", "csr", "pem");
-        if (p == null) {
-            return;
-        }
-        try {
-            CertificationRequest csr = new CertificationRequest(new BytesReader(UIUtils.openDERorPEM(p,
-                    "CERTIFICATE REQUEST")), false);
-            final IssueDialog diag = new IssueDialog(csr, ca.getTemplates());
-            diag.setLocationRelativeTo(this);
-            diag.setVisible(true);
-            final Template res = diag.getRes();
-            if (res == null) {
-                return;
-            }
-            ca.signCert(csr.getCertificationRequestInfo(), res);
-            onSave(null);
-        } catch (IOException | ParseException | NoSuchAlgorithmException | SignatureException | InvalidKeyException e) {
-            alert(rootPanel, "Issue new certificate", e);
-        }
-    }
-
-    /**
-     * EFFECTS: Show the new template dialog and add a template.
-     * MODIFIES: this
-     */
-    private void onNewTemplate(ActionEvent ev) {
-        final TemplateEditDialog diag = new TemplateEditDialog(temp ->
-                ca.getTemplates().stream().anyMatch(t -> t.getName().equals(temp)));
-        diag.pack();
-        diag.setLocationRelativeTo(this);
-        diag.setVisible(true);
-        final Template res = diag.getRes();
-        if (res == null) {
-            return;
-        }
-        ca.addTemplate(res);
-        unsaved.set(true);
-    }
-}
diff --git a/src/main/ui/MgmtScreen.java b/src/main/ui/MgmtScreen.java
deleted file mode 100644
index c630a34..0000000
--- a/src/main/ui/MgmtScreen.java
+++ /dev/null
@@ -1,152 +0,0 @@
-package ui;
-
-import model.asn1.exceptions.InvalidCAException;
-import model.asn1.exceptions.ParseException;
-import model.asn1.parsing.BytesReader;
-import model.csr.CertificationRequest;
-import model.pki.cert.Certificate;
-import model.pki.cert.TbsCertificate;
-
-import java.security.NoSuchAlgorithmException;
-import java.util.Base64;
-
-/**
- * Manage the private key and CA certificate. It can print the public key, generate CSR, and install CA cert.
- */
-public class MgmtScreen implements UIHandler {
-    private final JCA session;
-
-    /**
-     * EFFECTS: Init with the parent session.
-     */
-    public MgmtScreen(JCA session) {
-        this.session = session;
-    }
-
-    /**
-     * EFFECTS: Print help
-     */
-    @Override
-    public void help() {
-        System.out.print("show\tView the public key and CA certificate\n"
-                + "genkey\tGenerate a RSA private key\n"
-                + "csr\tGenerate a CSR for a upper-level CA to sign\n"
-                + "install\tInstall a CA certificate\n"
-                + "exit\tGo to main menu\n"
-                + "help\tPrint this message\n");
-    }
-
-    /**
-     * EFFECTS: Format the public key and CA
-     */
-    @Override
-    public void show() {
-        if (session.getCa().getPublicKey() == null) {
-            System.out.println("No private key installed");
-        } else {
-            System.out.println("Public Key (RSA2048):");
-            System.out.printf("\tModules:\t\t%s\n", session.getCa().getPublicKey().getModulus().toString(10));
-            System.out.printf("\tPublic Exponent:\t%s\n",
-                    session.getCa().getPublicKey().getPublicExponent().toString(16));
-        }
-        if (!session.checkCA(true)) {
-            return;
-        }
-        final TbsCertificate info = session.getCa().getCertificate().getCertificate();
-        System.out.printf("Subject:\t%s\n", info.getSubject().toString());
-        System.out.printf("Issuer:\t%s\n", info.getIssuer().toString());
-        System.out.printf("Not Before:\t%s\n", info.getValidity().getNotBefore().getTimestamp());
-        System.out.printf("Not After:\t%s\n", info.getValidity().getNotAfter().getTimestamp());
-        System.out.printf("Signature:\t%s\n",
-                Base64.getEncoder().encodeToString(Utils.byteToByte(info.getSubjectPublicKeyInfo()
-                        .getSubjectPublicKey().getConvertedVal())));
-    }
-
-    /**
-     * EFFECT: Generate a CSR
-     * MODIFIES: session
-     */
-    private void handleCSR() {
-        if (!session.checkCA(false)) {
-            return;
-        }
-        try {
-            CertificationRequest req = session.getCa().signCSR();
-            System.out.println(Utils.toPEM(req.encodeDER(), "CERTIFICATE REQUEST"));
-            session.setUnsaved(true);
-        } catch (Throwable e) {
-            System.out.println(e.getMessage());
-        }
-    }
-
-    /**
-     * EFFECTS: Handle the 'install' command. Read incoming certificate and validate it.
-     * MODIFIES: session
-     */
-    private void handleInstall() {
-        if (!session.checkCA(false)) {
-            return;
-        }
-        try {
-            final Byte[] in = session.handleInputPEM("CERTIFICATE");
-            final Certificate cert = new Certificate(new BytesReader(in), false);
-            session.getCa().installCertificate(cert);
-            session.setUnsaved(true);
-        } catch (InvalidCAException | ParseException e) {
-            System.out.println(e.getMessage());
-        }
-    }
-
-    /**
-     * EFFECTS: Handle the 'genkey' command. Generate a RSA2048 private key.
-     * MODIFIES: session
-     */
-    private void handleGenKey() {
-        if (session.getCa().getPublicKey() != null) {
-            System.out.println("A private key is already installed.");
-        }
-        try {
-            session.getCa().generateKey();
-            session.setUnsaved(true);
-        } catch (NoSuchAlgorithmException e) {
-            System.out.println(e.getMessage());
-        }
-    }
-
-    /**
-     * EFFECTS: Handle commands.
-     */
-    @Override
-    public void command(String... args) {
-        switch (args[0]) {
-            case "genkey":
-                handleGenKey();
-                break;
-            case "csr":
-                handleCSR();
-                break;
-            case "install":
-                handleInstall();
-                break;
-            default:
-                help();
-                break;
-        }
-    }
-
-    /**
-     * EFFECTS: Go to main menu
-     */
-    @Override
-    public Screen exit() {
-        return Screen.MAIN;
-    }
-
-    /**
-     * EFFECTS: return "/ca/ #"
-     */
-    @Override
-    public String getPS1() {
-        return "/ca/ #";
-    }
-}
\ No newline at end of file
diff --git a/src/main/ui/RevokeDialog.java b/src/main/ui/RevokeDialog.java
deleted file mode 100644
index ad0d4be..0000000
--- a/src/main/ui/RevokeDialog.java
+++ /dev/null
@@ -1,184 +0,0 @@
-package ui;
-
-import model.asn1.ASN1Object;
-import model.asn1.UtcTime;
-import model.pki.cert.Certificate;
-import model.pki.crl.Reason;
-import model.pki.crl.RevokedCertificate;
-import ui.widgets.GCBuilder;
-import ui.widgets.UIUtils;
-
-import javax.swing.*;
-import java.awt.*;
-import java.awt.event.ActionEvent;
-import java.awt.event.KeyEvent;
-import java.awt.event.WindowAdapter;
-import java.awt.event.WindowEvent;
-import java.time.ZoneId;
-import java.time.ZonedDateTime;
-import java.time.format.DateTimeFormatter;
-import java.time.format.DateTimeParseException;
-import java.util.Arrays;
-
-import static java.awt.GridBagConstraints.HORIZONTAL;
-import static java.awt.GridBagConstraints.WEST;
-import static ui.widgets.UIUtils.alert;
-
-/**
- * A dialog that presents user with cert info, revocation reason, and revocation time.
- * +----------------------------+
- * |Revoking: CN=xyz (Serial: 1)|
- * |Reason:   (Drop Down)       |
- * |Time:     (ISO-8601 text)   |
- * |                            |
- * |               Revoke Cancel|
- * +----------------------------+
- */
-public class RevokeDialog extends JDialog {
-    /**
-     * ISO8601
-     */
-    private static final DateTimeFormatter DATE_FORMAT = DateTimeFormatter.ISO_OFFSET_DATE_TIME;
-
-    /**
-     * The incoming certificate.
-     */
-    private final Certificate crt;
-
-    /**
-     * The result.
-     */
-    private RevokedCertificate res;
-
-
-    /**
-     * Root pane
-     */
-    private JPanel contentPane;
-
-    /**
-     * OK button
-     */
-    private JButton buttonOK;
-
-    /**
-     * Cancel button
-     */
-    private JButton buttonCancel;
-
-    /**
-     * Reason
-     */
-    private JComboBox<String> comboBoxReason;
-
-    /**
-     * Subject (not editable)
-     */
-    private JTextField textFieldSubject;
-
-    /**
-     * Time
-     */
-    private JFormattedTextField formattedTextFieldTime;
-
-    /**
-     * EFFECTS: Init GUI with the given cert.
-     */
-    public RevokeDialog(Certificate crt) {
-        this.crt = crt;
-
-        contentPane = new JPanel();
-        contentPane.setLayout(new BoxLayout(contentPane, BoxLayout.PAGE_AXIS));
-        contentPane.setBorder(BorderFactory.createEmptyBorder(8, 8, 8, 8));
-        contentPane.add(renderForm());
-
-        contentPane.add(UIUtils.createActionsPane(buttonOK = new JButton("Revoke"),
-                        buttonCancel = new JButton("Cancel")));
-        buttonOK.addActionListener(this::onOK);
-        buttonCancel.addActionListener(this::onCancel);
-
-        setContentPane(contentPane);
-        setModal(true);
-        getRootPane().setDefaultButton(buttonOK);
-        setDefaultCloseOperation(DO_NOTHING_ON_CLOSE);
-
-        setTitle("Revoke certificate");
-
-        addWindowListener(new WindowAdapter() {
-            public void windowClosing(WindowEvent e) {
-                onCancel(null);
-            }
-        });
-
-        contentPane.registerKeyboardAction(this::onCancel,
-                KeyStroke.getKeyStroke(KeyEvent.VK_ESCAPE, 0),
-                JComponent.WHEN_ANCESTOR_OF_FOCUSED_COMPONENT);
-    }
-
-    /**
-     * EFFECTS: Init GUI.
-     * MODIFIES: this
-     */
-    private JPanel renderForm() {
-        final JPanel panelForm = new JPanel();
-        panelForm.setLayout(new GridBagLayout());
-
-        panelForm.add(new JLabel("Revoking: "), new GCBuilder().anchor(WEST).build());
-        panelForm.add(new JLabel("Reason: "), new GCBuilder().gridY(1).anchor(WEST).build());
-        panelForm.add(new JLabel("Time: "), new GCBuilder().gridY(2).anchor(WEST).build());
-
-        textFieldSubject = new JTextField(String.format("%s (Serial: %d)",
-                crt.getCertificate().getSubject().toString(), crt.getCertificate().getSerialNumber().getLong()));
-        textFieldSubject.setEditable(false);
-        panelForm.add(textFieldSubject, new GCBuilder().gridX(1).anchor(WEST).fill(HORIZONTAL).build());
-
-        comboBoxReason = new JComboBox<>(Arrays.stream(Reason.values()).map(Enum::toString).toArray(String[]::new));
-        panelForm.add(comboBoxReason, new GCBuilder().gridXY(1, 1).anchor(WEST).fill(HORIZONTAL).build());
-
-        formattedTextFieldTime = new JFormattedTextField(DATE_FORMAT.toFormat());
-        formattedTextFieldTime.setText(ZonedDateTime.now().format(DATE_FORMAT));
-        panelForm.add(formattedTextFieldTime, new GCBuilder().gridXY(1, 2).anchor(WEST).fill(HORIZONTAL).build());
-
-        panelForm.add(new JPanel(), new GCBuilder().gridXY(1, 3).expandXY().fill(HORIZONTAL).build());
-        return panelForm;
-    }
-
-    /**
-     * EFFECTS: Validate form, set result, and close dialog.
-     *          Time must be a valid ISO-8601 string with offset, and it will be converted into UTC.
-     *          Reason must be supported.
-     * MODIFIES: this
-     */
-    private void onOK(ActionEvent ev) {
-        try {
-            res = new RevokedCertificate(ASN1Object.TAG_SEQUENCE, null,
-                    crt.getCertificate().getSerialNumber(),
-                    new UtcTime(UtcTime.TAG, null,
-                            ZonedDateTime.parse(formattedTextFieldTime.getText(), DATE_FORMAT)
-                                    .withZoneSameInstant(ZoneId.of("UTC"))),
-                    Reason.valueOf(comboBoxReason.getSelectedItem().toString()));
-            dispose();
-        } catch (DateTimeParseException e) {
-            alert(rootPane, "Revoke certificate", "Invalid time: " + formattedTextFieldTime.getText()
-                    + ". It must be a valid ISO8601 time with offset, like '1919-08-10T11:45:14+09:00'.");
-        } catch (IllegalArgumentException e) {
-            alert(rootPane, "Revoke certificate", "Invalid reason.");
-        }
-    }
-
-    /**
-     * EFFECTS: Clear the result and close dialog.
-     * MODIFIES: this
-     */
-    private void onCancel(ActionEvent ev) {
-        res = null;
-        dispose();
-    }
-
-    /**
-     * EFFECTS: Get result.
-     */
-    public RevokedCertificate getRes() {
-        return res;
-    }
-}
diff --git a/src/main/ui/Screen.java b/src/main/ui/Screen.java
deleted file mode 100644
index 31370e1..0000000
--- a/src/main/ui/Screen.java
+++ /dev/null
@@ -1,31 +0,0 @@
-package ui;
-
-/**
- * The screen type
- */
-public enum Screen {
-    /**
-     * Main menu (mgmt, issue, template, crl, show, revoke, log)
-     */
-    MAIN,
-
-    /**
-     * The CA management menu (show, csr, install)
-     */
-    MGMT,
-
-    /**
-     * The issue menu (show, set, commit)
-     */
-    ISSUE,
-
-    /**
-     * The templates menu (show, add, enable, disable, remove)
-     */
-    TEMPLATES,
-
-    /**
-     * The template edit menu (show, set, commit)
-     */
-    TEMPLATE_SET
-}
diff --git a/src/main/ui/TemplateEditDialog.java b/src/main/ui/TemplateEditDialog.java
deleted file mode 100644
index a3986de..0000000
--- a/src/main/ui/TemplateEditDialog.java
+++ /dev/null
@@ -1,73 +0,0 @@
-package ui;
-
-import model.asn1.exceptions.ParseException;
-import model.ca.Template;
-import model.x501.Name;
-import ui.widgets.CertEditDialog;
-
-import javax.swing.*;
-import java.awt.event.ActionEvent;
-import java.util.function.Function;
-
-import static ui.widgets.UIUtils.alert;
-
-/**
- * A dialog that allows users to input template name, subject, and validity.
- */
-public class TemplateEditDialog extends CertEditDialog<Template> {
-    /**
-     * Callback function to check for name conflict.
-     */
-    private final Function<String, Boolean> dupDetector;
-
-    /**
-     * Text field for name.
-     */
-    private JTextField templateComponent;
-
-    /**
-     * EFFECTS: Init UI, title = New Template, OK button = Add, set dup detector.
-     */
-    public TemplateEditDialog(Function<String, Boolean> dupDetector) {
-        super();
-        this.dupDetector = dupDetector;
-        setTitle("New template");
-        buttonOK.setText("Add");
-    }
-
-    /**
-     * EFFECTS: Initialize the subject text field with JTextField.
-     * MODIFIES: this
-     */
-    @Override
-    protected JComponent createTemplateComponent() {
-        return templateComponent = new JTextField();
-    }
-
-    /**
-     * EFFECTS: Validate the form, set the result, and close the dialog.
-     *          Name must not be null; Name must not conflict; Subject must be valid.
-     * MODIFIES: this
-     */
-    @Override
-    protected void onOK(ActionEvent ev) {
-        if (templateComponent.getText().isEmpty()) {
-            alert(rootPane, getTitle(), "The template name must not be empty.");
-            return;
-        }
-        if (dupDetector.apply(templateComponent.getText())) {
-            alert(rootPane, getTitle(), "The template exists.");
-            return;
-        }
-
-        try {
-            res = new Template(templateComponent.getText(),
-                    false,
-                    textFieldSubject.getText().isBlank() ? null : Name.parseString(textFieldSubject.getText()),
-                    (Integer) spinnerValidity.getValue());
-            dispose();
-        } catch (ParseException e) {
-            alert(rootPane, getTitle(), e);
-        }
-    }
-}
diff --git a/src/main/ui/TemplateSetScreen.java b/src/main/ui/TemplateSetScreen.java
deleted file mode 100644
index 30d25b9..0000000
--- a/src/main/ui/TemplateSetScreen.java
+++ /dev/null
@@ -1,157 +0,0 @@
-package ui;
-
-import model.asn1.exceptions.ParseException;
-import model.ca.Template;
-import model.x501.Name;
-
-/**
- * The screen that modifies the properties of a single template and add it to the store.
- */
-public class TemplateSetScreen implements UIHandler {
-    private final JCA session;
-
-    /**
-     * EFFECTS: Init with session.
-     */
-    public TemplateSetScreen(JCA session) {
-        this.session = session;
-    }
-
-    private Template template;
-
-    /**
-     * EFFECTS: Print help
-     */
-    @Override
-    public void help() {
-        System.out.println("show\tView the current template settings\n"
-                + "set\tSet key value\n"
-                + "commit\tSave the template\n"
-                + "exit\tDiscard changes\n"
-                + "help\tPrint this help message\n");
-    }
-
-    /**
-     * EFFECTS: Parse and set / unset the subject of the template
-     * MODIFIES: this
-     */
-    private void handleSetSubject(String val) {
-        try {
-            if (val == null) {
-                template = new Template(template.getName(), template.isEnabled(), (Name) null, template.getValidity());
-            } else {
-                template = new Template(template.getName(), template.isEnabled(), val, template.getValidity());
-            }
-        } catch (ParseException e) {
-            System.out.println(e.getMessage());
-        }
-    }
-
-    /**
-     * EFFECTS: Set the validity of the template to the given integer
-     * MODIFIES: this
-     */
-    private void handleSetValidity(String val) {
-        if (val == null) {
-            System.out.println("Cannot unset validity");
-            return;
-        }
-        try {
-            long i = Long.parseLong(val);
-            if (i <= 0) {
-                System.out.println("Invalid validity days");
-                return;
-            }
-            template = new Template(template.getName(), template.isEnabled(), template.getSubject(), i);
-        } catch (NumberFormatException ignored) {
-            System.out.println("Invalid validity days");
-        }
-    }
-
-    /**
-     * EFFECTS: Handle the `set` command.
-     * MODIFIES: this
-     */
-    private void handleSet(String... args) {
-        if (args.length != 2 && args.length != 3) {
-            System.out.println("Usage: set <key> <value>");
-            System.out.println("Supported keys: subject validity");
-            return;
-        }
-        String val = args.length == 3 ? args[2] : null;
-        switch (args[1]) {
-            case "subject":
-                handleSetSubject(val);
-                break;
-            case "validity":
-                handleSetValidity(val);
-                break;
-            default:
-                System.out.println("Unknown key");
-                break;
-        }
-    }
-
-    /**
-     * EFFECTS: Add the template to store and switch to templates screen.
-     * MODIFIES: session
-     */
-    @Override
-    public void commit() {
-        session.getCa().addTemplate(template);
-        session.setUnsaved(true);
-        session.setScreen(Screen.TEMPLATES);
-    }
-
-    /**
-     * EFFECTS: Show template info.
-     */
-    @Override
-    public void show() {
-        System.out.println("Subject:\t" + template.getSubject());
-        System.out.println("Validity:\t" + template.getValidity() + " days");
-    }
-
-    /**
-     * EFFECTS: Handle commands
-     */
-    @Override
-    public void command(String... args) {
-        switch (args[0]) {
-            case "set":
-                handleSet(args);
-                break;
-            default:
-            case "help":
-                help();
-                break;
-        }
-    }
-
-    /**
-     * EFFECTS: Return to templates list and clear the current template in editing.
-     */
-    @Override
-    public Screen exit() {
-        template = null;
-        return Screen.TEMPLATES;
-    }
-
-    /**
-     * EFFECTS: yuuta@JCA /templates/name/ %
-     */
-    @Override
-    public String getPS1() {
-        return String.format("/templates/%s/ %%", template.getName());
-    }
-
-    /**
-     * EFFECT: Edit args[0].
-     * REQUIRES: args.length = 1; args[0] instanceof Template
-     * MODIFIES: args[0]
-     */
-    @Override
-    public void enter(Object... args) {
-        template = (Template) args[0];
-    }
-}
\ No newline at end of file
diff --git a/src/main/ui/TemplatesScreen.java b/src/main/ui/TemplatesScreen.java
deleted file mode 100644
index e622709..0000000
--- a/src/main/ui/TemplatesScreen.java
+++ /dev/null
@@ -1,138 +0,0 @@
-package ui;
-
-import model.ca.Template;
-import model.x501.Name;
-
-/**
- * The screen that allows users to list templates and manage them.
- */
-public class TemplatesScreen implements UIHandler {
-    private final JCA session;
-
-    /**
-     * EFFECTS: Init with the session.
-     */
-    public TemplatesScreen(JCA session) {
-        this.session = session;
-    }
-
-    /**
-     * EFFECTS: Print help.
-     */
-    @Override
-    public void help() {
-        System.out.println("show\tList templates\n"
-                + "add\tCreate a new template\n"
-                + "enable\tEnable a template\n"
-                + "disable\tDisable a template\n"
-                + "delete\tDelete a template\n"
-                + "exit\tGo to main menu\n"
-                + "help\tPrint this message");
-    }
-
-    /**
-     * EFFECTS: List templates in Name[ENABLED / DISABLED] Subject Validity format.
-     */
-    @Override
-    public void show() {
-        session.getCa().getTemplates().forEach(tem ->
-                System.out.printf("%s[%s]\t%s\t%d Days\n",
-                        tem.getName(),
-                        tem.isEnabled() ? "ENABLED" : "DISABLED",
-                        tem.getSubject(),
-                        tem.getValidity()));
-    }
-
-    /**
-     * EFFECTS: Create a new template with the given name and switch to the template set screen.
-     */
-    private void handleAdd(String... args) {
-        if (args.length <= 1) {
-            System.out.println("Usage: add <name>");
-            return;
-        }
-        if (session.getCa().findTemplate(args[1], false) != null) {
-            System.out.println("The template already exists.");
-            return;
-        }
-
-        session.setScreen(Screen.TEMPLATE_SET,
-                new Template(args[1], false, (Name) null, 30));
-    }
-
-    /**
-     * EFFECTS: Handle the enable / disable commands.
-     * MODIFIES: session
-     */
-    private void handleEnableDisable(boolean enable, String... args) {
-        if (args.length <= 1) {
-            System.out.printf("Usage: %s <template>\n", enable ? "enable" : "disable");
-            return;
-        }
-        Template tmp = session.getCa().findTemplate(args[1], false);
-        if (tmp == null) {
-            System.out.println("Cannot find the template specified");
-            return;
-        }
-        session.getCa().setTemplateEnable(tmp, enable);
-        session.setUnsaved(true);
-    }
-
-    /**
-     * EFFECTS: Handle the delete command
-     * MODIFIES: session
-     */
-    private void handleDelete(String... args) {
-        if (args.length <= 1) {
-            System.out.println("Usage: delete <template>");
-            return;
-        }
-        Template tmp = session.getCa().findTemplate(args[1], true);
-        if (tmp == null) {
-            System.out.println("Cannot find the template specified");
-            return;
-        }
-        session.getCa().removeTemplate(tmp);
-        session.setUnsaved(true);
-    }
-
-    /**
-     * EFFECTS: Handle commands.
-     */
-    @Override
-    public void command(String... args) {
-        switch (args[0]) {
-            case "add":
-                handleAdd(args);
-                break;
-            case "enable":
-                handleEnableDisable(true, args);
-                break;
-            case "disable":
-                handleEnableDisable(false, args);
-                break;
-            case "delete":
-                handleDelete(args);
-                break;
-            default:
-                help();
-                break;
-        }
-    }
-
-    /**
-     * EFFECTS: Go to main menu.
-     */
-    @Override
-    public Screen exit() {
-        return Screen.MAIN;
-    }
-
-    /**
-     * EFFECTS: Return "/templates/ %"
-     */
-    @Override
-    public String getPS1() {
-        return "/templates/ %";
-    }
-}
diff --git a/src/main/ui/UIHandler.java b/src/main/ui/UIHandler.java
deleted file mode 100644
index f451542..0000000
--- a/src/main/ui/UIHandler.java
+++ /dev/null
@@ -1,45 +0,0 @@
-package ui;
-
-/**
- * Represents a screen
- */
-public interface UIHandler {
-    /**
-     * EFFECTS: Called when the screen is switched to.
-     */
-    default void enter(Object... args) {
-
-    }
-
-    /**
-     * EFFECTS: Show objects. command() will not be called.
-     */
-    void show();
-
-    /**
-     * EFFECTS: Commit changes and exit. command() will not be called.
-     */
-    default void commit() {
-    }
-
-    /**
-     * EFFECTS: Discard changes and exit. command() will not be called. Returns the next screen.
-     */
-    Screen exit();
-
-    /**
-     * EFFECTS: Run help. command() will not be called.
-     */
-    void help();
-
-    /**
-     * EFFECTS: Any commands rather than commit / exit / help.
-     * REQUIRES: args != null && args.length >= 1
-     */
-    void command(String... args);
-
-    /**
-     * EFFECTS: Return the current PS1 prompt.
-     */
-    String getPS1();
-}
diff --git a/src/main/ui/gui/IssueDialog.java b/src/main/ui/gui/IssueDialog.java
new file mode 100644
index 0000000..8dcd6a8
--- /dev/null
+++ b/src/main/ui/gui/IssueDialog.java
@@ -0,0 +1,101 @@
+package ui.gui;
+
+import model.asn1.exceptions.ParseException;
+import model.ca.Template;
+import model.csr.CertificationRequest;
+import model.x501.Name;
+import ui.gui.widgets.CertEditDialog;
+
+import javax.swing.*;
+import java.awt.event.ActionEvent;
+import java.util.List;
+
+import static ui.gui.widgets.UIUtils.alert;
+
+/**
+ * Dialog that allows user to choose a template and edit the incoming CSR properties to get it signed.
+ */
+public class IssueDialog extends CertEditDialog<Template> {
+    /**
+     * The list of templates.
+     */
+    private final List<Template> templates;
+
+    /**
+     * The incoming CSR.
+     */
+    private final CertificationRequest csr;
+
+    /**
+     * Combo box to choose template.
+     */
+    private JComboBox<String> componentTemp;
+
+    /**
+     * The selected template, immutable.
+     */
+    private Template selectedTemplate;
+
+    /**
+     * EFFECTS: Init the dialog with CSR and templates.
+     * REQUIRES: csr must have a subject; templates must have at least one enabled.
+     */
+    public IssueDialog(CertificationRequest csr, List<Template> templates) {
+        super();
+        this.csr = csr;
+        this.templates = templates;
+
+        setTitle("Issue new certificate");
+        buttonOK.setText("Issue");
+        componentTemp.setModel(new DefaultComboBoxModel<>(templates.stream()
+                .filter(Template::isEnabled).map(Template::getName).toArray(String[]::new)));
+        componentTemp.addActionListener(this::onTemplateChange);
+
+        onTemplateChange(null);
+        pack();
+    }
+
+    /**
+     * EFFECTS: Create the templates combo box.
+     * MODIFIES: this
+     */
+    @Override
+    protected JComponent createTemplateComponent() {
+        return componentTemp = new JComboBox<>();
+    }
+
+    /**
+     * EFFECTS: Validate the form, compose a resulting template, close the dialog.
+     * MODIFIES: this
+     */
+    @Override
+    protected void onOK(ActionEvent ev) {
+        if (textFieldSubject.getText().isEmpty()) {
+            alert(this, getTitle(), "Subject must not be empty.");
+            return;
+        }
+        try {
+            res = new Template(selectedTemplate.getName(),
+                    true,
+                    Name.parseString(textFieldSubject.getText()),
+                    ((SpinnerNumberModel) spinnerValidity.getModel()).getNumber().longValue());
+            dispose();
+        } catch (ParseException e) {
+            alert(this, getTitle(), e);
+        }
+    }
+
+    /**
+     * EFFECTS: Handle template change, rewrite the form with the new template.
+     * MODIFIES: this
+     */
+    private void onTemplateChange(ActionEvent ae) {
+        selectedTemplate = templates.stream()
+                .filter(temp -> temp.getName().equals(componentTemp.getSelectedItem()))
+                .findFirst()
+                .get();
+        textFieldSubject.setText(selectedTemplate.getSubject() != null ? selectedTemplate.getSubject().toString() :
+                csr.getCertificationRequestInfo().getSubject().toString());
+        spinnerValidity.setValue(selectedTemplate.getValidity());
+    }
+}
diff --git a/src/main/ui/gui/MainUI.java b/src/main/ui/gui/MainUI.java
new file mode 100644
index 0000000..9fa65ef
--- /dev/null
+++ b/src/main/ui/gui/MainUI.java
@@ -0,0 +1,696 @@
+package ui.gui;
+
+import model.GroupObserver;
+import model.ObservedData;
+import model.Observer;
+import model.asn1.exceptions.InvalidCAException;
+import model.asn1.exceptions.InvalidDBException;
+import model.asn1.exceptions.ParseException;
+import model.asn1.parsing.BytesReader;
+import model.ca.AuditLogEntry;
+import model.ca.CertificationAuthority;
+import model.ca.Template;
+import model.csr.CertificationRequest;
+import model.pki.cert.Certificate;
+import model.pki.crl.CertificateList;
+import model.pki.crl.RevokedCertificate;
+import persistence.Decoder;
+import persistence.FS;
+import ui.Utils;
+import ui.gui.widgets.*;
+
+import javax.swing.*;
+import javax.swing.event.ChangeEvent;
+import java.awt.*;
+import java.awt.event.ActionEvent;
+import java.io.IOException;
+import java.io.OutputStream;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.StandardOpenOption;
+import java.security.InvalidKeyException;
+import java.security.NoSuchAlgorithmException;
+import java.security.SignatureException;
+import java.security.interfaces.RSAPublicKey;
+
+import static java.awt.GridBagConstraints.*;
+import static ui.gui.widgets.UIUtils.*;
+
+/**
+ * The main GUI.
+ * +------------------------------++------------------------------++------------------------------+
+ * |  JCA                       X ||  JCA                       X ||  JCA                       X |
+ * +------------------------------++------------------------------++------------------------------+
+ * |Load Save                  CSR||Load Save   Sign Revoke Export||Load Save      New Ena Dis Del|
+ * +----+-------+-----------+-----++----+-------+----------+------++----+-------+-----------------+
+ * | CA | Certs | Templates |     || CA | Certs | Templates|      || CA | Certs | Templates       |
+ * +----+-------+-----------+-----++-+--+-----+-+----+-----+------++-+--+---+---+-----+-----------+
+ * | Welcome to JCA               || | Serial | Subj | Bef | To   || | Name | Subj    |  Validity |
+ * |                              |+-+--------+------+-----+------++-+------+---------+-----------+
+ * | Private key:    Generate     ||      (Issued Certs)          ||      (All Templates)         |
+ * | CA certificate: Install CSR  ||                              ||                              |
+ * +------------------------------++------------------------------++------------------------------+
+ * +-----+----------+-------------++-----+----------+-------------++-----+----------+-------------+
+ * |Time | Operator | Action      ||Time | Operator | Action      ||Time | Operator | Action      |
+ * +-----+----------+-------------++-----+----------+-------------++-----+----------+-------------+
+ * |  (Audit Logs)                ||  (Audit Logs)                ||  (Audit Logs)                |
+ * +------------------------------++------------------------------++------------------------------+
+ * | Ready: (Last operation)      || Unsaved: (Last operation)    || Ready: (Last Operation)      |
+ * +------------------------------++------------------------------++------------------------------+
+ */
+public class MainUI extends JFrame {
+    /**
+     * Default db file (./data/ca.json)
+     */
+    private static final Path PATH_DEFAULT = Path.of("data", "ca.json");
+
+    /**
+     * The root panel (Box layout).
+     */
+    private final JPanel rootPanel = new JPanel(new BoxLayout(rootPane, BoxLayout.PAGE_AXIS));
+
+    /**
+     * Common toolbar buttons
+     */
+    private final JButton buttonToolbarLoad = btn("Load", "open.png", this::onLoad);
+    private final JButton buttonToolbarSave = btn("Save", "saveall.png", this::onSave);
+
+    /**
+     * Toolbar that switches with the tab.
+     */
+    private final JPanel panelContextAwareToolbar = new JPanel(new CardLayout(0, 0));
+
+    /**
+     * Tab root.
+     */
+    private final JTabbedPane tabbedPane = new JTabbedPane();
+
+    /**
+     * CA tab
+     */
+    private final JLabel labelCACertificate = new JLabel();
+    private final JLabel labelPrivateKey = new JLabel();
+    private final JButton buttonGenPrivKey = btn("Generate", 'G', this::onGeneratePrivateKey);
+    private final JButton buttonInstallCA = btn("Install", 'I', this::onInstallCA);
+    private final JButton buttonGenCSR = btn("CSR", this::onSignCSR);
+    private final QRPanel panelQR = new QRPanel(256);
+    private final JToolBar toolbarCA = new JToolBar();
+    private final JButton buttonCAToolbarCRL = btn("CRL", "publisher.png", this::onCRL);
+
+    /**
+     * Certs tab
+     */
+    private JPanel panelCertsTab;
+    private final JTable tableCerts = new JTable();
+    private final CertTableModel modelCerts = new CertTableModel();
+    private final JToolBar toolbarCerts = new JToolBar();
+    private final JButton buttonCertsToolbarNew = btn("Sign", "new.png", this::onIssue);
+    private final JButton buttonCertsToolbarRevoke = btn("Revoke", "deletetest.png", this::onRevokeCert);
+    private final JButton buttonCertsToolbarExport = btn("Export", "export.png", this::onExportCert);
+
+    /**
+     * Templates tab
+     */
+    private JPanel panelTmpTab;
+    private final JTable tableTemplates = new JTable();
+    private final TemplateTableModel modelTemplates = new TemplateTableModel();
+    private final JToolBar toolbarTemplates = new JToolBar();
+    private final JButton buttonTemplatesToolbarNew = btn("New", "new.png", this::onNewTemplate);
+    private final JButton buttonTemplatesToolbarEnable = btn("Enable", "enable.png", this::onEnableTemplate);
+    private final JButton buttonTemplatesToolbarDisable = btn("Disable", "disable.png", this::onDisableTemplate);
+    private final JButton buttonTemplatesToolbarDelete = btn("Delete", "deletetest.png", this::onDeleteTemplate);
+
+    /**
+     * Logs region
+     */
+    private final JPanel panelLogs;
+    private final JTable tableAuditLogs = new JTable();
+    private final LogTableModel modelAuditLogs = new LogTableModel();
+
+    /**
+     * Status region
+     */
+    private final JLabel labelStatus = new JLabel();
+    private ObservedData<Boolean> unsaved = new ObservedData<>(false, this::acceptUnsaved);
+
+    /**
+     * CA and observers
+     */
+    private CertificationAuthority ca;
+
+    private final GroupObserver obs = new GroupObserver();
+
+    /**
+     * EFFECTS: Setup the CA and GUI.
+     */
+    public MainUI() {
+        setTitle("JCA");
+        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
+
+        setContentPane(rootPanel);
+        rootPanel.setLayout(new BoxLayout(rootPanel, BoxLayout.PAGE_AXIS));
+
+        rootPanel.add(setupToolbar());
+        final JSplitPane splitPane = new JSplitPane(0);
+        rootPanel.add(splitPane);
+        splitPane.setLeftComponent(setupTabs());
+        rootPanel.getRootPane().setDefaultButton(buttonGenPrivKey);
+
+        splitPane.setRightComponent(panelLogs = defView(scrTbl(tableAuditLogs), "No audit logs"));
+        panelLogs.setPreferredSize(new Dimension(panelLogs.getPreferredSize().width,
+                panelLogs.getPreferredSize().height / 2));
+        panelLogs.setBackground(new Color(-1));
+
+        rootPanel.add(labelStatus);
+        labelStatus.setBorder(BorderFactory.createEmptyBorder(4, 8, 8, 8));
+
+        ca = new CertificationAuthority();
+
+        tableAuditLogs.setModel(modelAuditLogs);
+        tableCerts.setModel(modelCerts);
+        tableTemplates.setModel(modelTemplates);
+
+        tabbedPane.addChangeListener(this::onChangeTab);
+        setupObservers();
+
+        setCA(ca);
+    }
+
+    // -----BEGIN HELPER METHODS-----
+
+    /**
+     * EFFECTS: Rewind the CA and refresh all pages.
+     * MODIFIES: ca (observer), this
+     */
+    private void setCA(CertificationAuthority ca) {
+        this.ca = ca;
+        ca.registerObserver(obs);
+
+        modelAuditLogs.setPtrData(ca.getLogs());
+        modelCerts.setPtrData(ca.getSigned());
+        modelCerts.setPtrRevokedData(ca.getRevoked());
+        modelTemplates.setPtrData(ca.getTemplates());
+
+        renderRefresh();
+    }
+
+    /**
+     * EFFECTS: Set the QR code data to either null (no public key) or PEM-encoded PKCS#1 public key.
+     */
+    private void renderQRPublicKey() {
+        if (ca.getPublicKey() == null) {
+            panelQR.setData(null);
+            return;
+        }
+        panelQR.setData(Utils.toPEM(Utils.byteToByte(ca.getPublicKey().getEncoded()), "PUBLIC KEY"));
+    }
+
+    // -----END HELPER METHODS-----
+
+    // -----BEGIN DATA OBSERVERS-----
+
+    /**
+     * EFFECTS: Setup observers
+     * MODIFIES: this
+     */
+    private void setupObservers() {
+        obs.register(AuditLogEntry.class, this::acceptAuditLog);
+        obs.register(Certificate.class, this::acceptCertificate);
+        obs.register(RSAPublicKey.class, this::acceptPrivateKey);
+        obs.register(Template.class, this::acceptTemplate);
+    }
+
+    /**
+     * EFFECTS: Handle new audit log, hide default text, notify the model
+     * MODIFIES: this
+     * REQUIRES: direction == ADD, i >= 0
+     */
+    private void acceptAuditLog(AuditLogEntry auditLogEntry, int direction, int i) {
+        setContentVisible(panelLogs, true);
+        modelAuditLogs.fireTableRowsInserted(ca.getLogs().size() - 1, ca.getLogs().size() - 1);
+        acceptUnsaved(unsaved.get(), Observer.DIRECTION_CHANGE, Observer.INDEX_NOT_IN_LIST);
+    }
+
+    /**
+     * EFFECTS: Handle CA cert or new issued cert, notify CA page or model accordingly, hide certs default text
+     * MODIFIES: this
+     * REQUIRES: direction == CHANGE or ADD, i >= 0 or -1
+     */
+    private void acceptCertificate(Certificate cert, int direction, int i) {
+        if (i == Observer.INDEX_NOT_IN_LIST) {
+            renderCAPage();
+        } else {
+            setContentVisible(panelCertsTab, true);
+            modelCerts.fireTableRowsInserted(i, i);
+        }
+    }
+
+    /**
+     * EFFECTS: Handle added, changed, or deleted template; notify model, show / hide default text.
+     * MODIFIES: this
+     * REQUIRES: i >= 0.
+     */
+    private void acceptTemplate(Template template, int direction, int i) {
+        setContentVisible(panelTmpTab, !ca.getTemplates().isEmpty());
+        switch (direction) {
+            case Observer.DIRECTION_ADD:
+                modelTemplates.fireTableRowsInserted(i, i);
+                break;
+            case Observer.DIRECTION_CHANGE:
+                modelTemplates.fireTableRowsUpdated(i, i);
+                break;
+            case Observer.DIRECTION_REMOVE:
+                modelTemplates.fireTableRowsDeleted(i, i);
+                break;
+        }
+    }
+
+    /**
+     * EFFECTS: Handle added private key. Change buttons / labels accordingly.
+     * MODIFIES: this
+     */
+    private void acceptPrivateKey(RSAPublicKey pubKey, int direction, int i) {
+        renderCAPage();
+    }
+
+    /**
+     * EFFECTS: Handle status label change, set status to unsaved / saved + latest action.
+     * MODIFIES: this
+     */
+    private void acceptUnsaved(Boolean unsaved, int direction, int i) {
+        labelStatus.setText(unsaved ? "Unsaved" : "Ready");
+        if (!ca.getLogs().isEmpty()) {
+            labelStatus.setText(labelStatus.getText() + ": " + ca.getLogs().get(ca.getLogs().size() - 1).getAction());
+        }
+    }
+
+    // -----END DATA OBSERVERS----
+
+    // -----BEGIN RENDERERS-----
+
+    /**
+     * EFFECTS: Setup the toolbar.
+     * MODIFIES: this
+     */
+    private JToolBar setupToolbar() {
+        final JToolBar toolBar = new JToolBar();
+        toolBar.setAlignmentX(Component.LEFT_ALIGNMENT);
+        toolBar.setBorder(BorderFactory.createEmptyBorder(4, 8, 4, 8));
+
+        toolBar.add(buttonToolbarLoad);
+        toolBar.add(buttonToolbarSave);
+
+        toolBar.add(panelContextAwareToolbar);
+
+        panelContextAwareToolbar.add(toolbarTemplates, "CardToolbarTemplates");
+
+        toolbarTemplates.add(Box.createHorizontalGlue());
+        toolbarTemplates.add(buttonTemplatesToolbarNew);
+        toolbarTemplates.add(buttonTemplatesToolbarEnable);
+        toolbarTemplates.add(buttonTemplatesToolbarDisable);
+        toolbarTemplates.add(buttonTemplatesToolbarDelete);
+
+        panelContextAwareToolbar.add(toolbarCerts, "CardToolbarCerts");
+        toolbarCerts.add(Box.createHorizontalGlue());
+        toolbarCerts.add(buttonCertsToolbarNew);
+        toolbarCerts.add(buttonCertsToolbarRevoke);
+        toolbarCerts.add(buttonCertsToolbarExport);
+
+        panelContextAwareToolbar.add(toolbarCA, "CardToolbarCA");
+        toolbarCA.add(Box.createHorizontalGlue());
+        toolbarCA.add(buttonCAToolbarCRL);
+        return toolBar;
+    }
+
+    /**
+     * EFFECTS: Setup the tabs
+     * MODIFIES: this
+     */
+    private JTabbedPane setupTabs() {
+        tabbedPane.setAlignmentX(Component.LEFT_ALIGNMENT);
+        tabbedPane.setBorder(BorderFactory.createEmptyBorder(8, 8, 4, 8));
+
+        final JPanel panelTabCA = new JPanel();
+        panelTabCA.setLayout(new GridBagLayout());
+        tabbedPane.addTab("CA", panelTabCA);
+
+        panelTabCA.add(new JLabel("Welcome to JCA"), new GCBuilder().anchor(WEST).insectTop(8).build());
+        panelTabCA.add(labelPrivateKey, new GCBuilder().gridY(1).anchor(WEST).build());
+        panelTabCA.add(labelCACertificate, new GCBuilder().gridY(2).anchor(WEST).build());
+        panelTabCA.add(buttonGenPrivKey, new GCBuilder().gridXY(1, 1).fill(HORIZONTAL).build());
+        panelTabCA.add(buttonInstallCA, new GCBuilder().gridXY(1, 2).fill(HORIZONTAL).build());
+        panelTabCA.add(buttonGenCSR, new GCBuilder().gridXY(2, 2).fill(HORIZONTAL).build());
+        panelTabCA.add(panelQR, new GCBuilder().gridY(3).fill(HORIZONTAL).build());
+        panelTabCA.add(new JPanel(), new GCBuilder().gridXY(4, 4).expandXY().fill(BOTH).build());
+        tabbedPane.addTab("Certs", panelCertsTab = defView(scrTbl(tableCerts), "No issued certs"));
+        tabbedPane.addTab("Templates", panelTmpTab = defView(scrTbl(tableTemplates), "No templates"));
+
+        return tabbedPane;
+    }
+
+    /**
+     * EFFECTS: Render public key and CA to the CA page and toolbar
+     * MODIFIES: this
+     */
+    private void renderCAPage() {
+        renderQRPublicKey();
+        if (ca.getPublicKey() == null) {
+            labelPrivateKey.setText("Private key not installed");
+        } else {
+            labelPrivateKey.setText(String.format("%s key: %s ...",
+                    ca.getPublicKey().getAlgorithm(),
+                    ca.getPublicKey().getModulus().toString(16).substring(0, 16)));
+        }
+        if (ca.getCertificate() == null) {
+            labelCACertificate.setText("CA certificate not installed");
+        } else {
+            labelCACertificate.setText(String.format("<html>CA: %s<br>Issued by: %s</html>",
+                    ca.getCertificate().getCertificate().getSubject().toString(),
+                    ca.getCertificate().getCertificate().getIssuer().toString()));
+        }
+        buttonGenPrivKey.setEnabled(ca.getPublicKey() == null);
+        buttonInstallCA.setEnabled(ca.getPublicKey() != null && ca.getCertificate() == null);
+        buttonGenCSR.setEnabled(ca.getPublicKey() != null && ca.getCertificate() == null);
+        buttonCertsToolbarNew.setEnabled(ca.getPublicKey() != null && ca.getCertificate() != null);
+        buttonCAToolbarCRL.setEnabled(ca.getPublicKey() != null && ca.getCertificate() != null);
+    }
+
+    /**
+     * EFFECTS: Reset all GUI to initial state and render the CA again.
+     * MODIFIES: this
+     */
+    private void renderRefresh() {
+        acceptUnsaved(false, Observer.DIRECTION_CHANGE, Observer.INDEX_NOT_IN_LIST);
+        onChangeTab(null);
+        renderCAPage();
+
+        modelAuditLogs.fireTableDataChanged();
+        setContentVisible(panelLogs, !ca.getLogs().isEmpty());
+
+        modelCerts.fireTableDataChanged();
+        setContentVisible(panelCertsTab, !ca.getSigned().isEmpty());
+
+        modelTemplates.fireTableDataChanged();
+        setContentVisible(panelTmpTab, !ca.getTemplates().isEmpty());
+    }
+
+    // -----END RENDERERS-----
+
+    // -----BEGIN ACTION LISTENERS-----
+
+    /**
+     * EFFECTS: Switch toolbar according to tab change.
+     * MODIFIES: this
+     */
+    private void onChangeTab(ChangeEvent ev) {
+        final CardLayout toolbarCardLayout = (CardLayout) panelContextAwareToolbar.getLayout();
+        switch (tabbedPane.getSelectedIndex()) {
+            case 0: {
+                toolbarCerts.setEnabled(false);
+                toolbarTemplates.setEnabled(false);
+                toolbarCardLayout.show(panelContextAwareToolbar, "CardToolbarCA");
+                break;
+            }
+            case 1: {
+                toolbarCerts.setEnabled(true);
+                toolbarTemplates.setEnabled(false);
+                toolbarCardLayout.show(panelContextAwareToolbar, "CardToolbarCerts");
+                break;
+            }
+            case 2: {
+                toolbarCerts.setEnabled(false);
+                toolbarTemplates.setEnabled(true);
+                toolbarCardLayout.show(panelContextAwareToolbar, "CardToolbarTemplates");
+                break;
+            }
+        }
+    }
+
+    /**
+     * EFFECTS: Generate private key.
+     * MODIFIES: this
+     * REQUIRES: No private key / CA is installed.
+     */
+    private void onGeneratePrivateKey(ActionEvent ev) {
+        try {
+            ca.generateKey();
+            unsaved.set(true);
+        } catch (NoSuchAlgorithmException e) {
+            alert(rootPanel, "Generate private key", e);
+        } finally {
+            renderCAPage();
+        }
+    }
+
+    /**
+     * EFFECTS: Sign a CSR and save to disk (in binary form).
+     * MODIFIES: this
+     * REQUIRES: Proper private key installed, no CA.
+     */
+    private void onSignCSR(ActionEvent ev) {
+        final Path p = chooseFile(rootPanel, "DER binary (*.csr)", "csr");
+        if (p == null) {
+            return;
+        }
+
+        try {
+            final OutputStream fd = Files.newOutputStream(p,
+                    StandardOpenOption.WRITE,
+                    StandardOpenOption.TRUNCATE_EXISTING,
+                    StandardOpenOption.CREATE);
+            final CertificationRequest csr = ca.signCSR();
+            fd.write(Utils.byteToByte(csr.encodeDER()));
+            fd.close();
+            unsaved.set(true);
+        } catch (IOException | ParseException | NoSuchAlgorithmException | SignatureException | InvalidKeyException e) {
+            alert(rootPanel, "Sign certification request", e);
+        }
+    }
+
+    /**
+     * EFFECTS: Pick a certificate and install.
+     * MODIFIES: this
+     * REQUIRES: Proper private key is installed, no CA.
+     */
+    private void onInstallCA(ActionEvent ev) {
+        final Path p = chooseFile(rootPanel, "DER X.509 certificate (*.crt, *.pem)", "crt", "pem");
+        if (p == null) {
+            return;
+        }
+
+        try {
+            final Certificate crt = new Certificate(new BytesReader(UIUtils.openDERorPEM(p, "CERTIFICATE")),
+                    false);
+            ca.installCertificate(crt);
+            unsaved.set(true);
+        } catch (IOException | ParseException | InvalidCAException e) {
+            alert(rootPanel, "Install CA", e);
+        } finally {
+            renderCAPage();
+        }
+    }
+
+    /**
+     * EFFECTS: Load the database and refresh.
+     * MODIFIES: this
+     */
+    private void onLoad(ActionEvent ev) {
+        if (unsaved.get()) {
+            alert(rootPanel, "Load database from filesystem",
+                    "Unable to load: current modifications are not saved.");
+            return;
+        }
+
+        try {
+            setCA(Decoder.decodeCA(FS.read(PATH_DEFAULT)));
+        } catch (NoSuchAlgorithmException | InvalidDBException e) {
+            alert(rootPanel, "Load database from filesystem", e);
+        }
+    }
+
+    /**
+     * EFFECTS: Save database.
+     * MODIFIES: this
+     */
+    private void onSave(ActionEvent ev) {
+        try {
+            FS.write(PATH_DEFAULT, Decoder.encodeCA(this.ca));
+            unsaved.set(false);
+        } catch (IOException e) {
+            alert(rootPanel, "Save database to filesystem", e);
+        }
+    }
+
+    /**
+     * EFFECTS: Enable a template.
+     * MODIFIES: this
+     */
+    private void onEnableTemplate(ActionEvent ev) {
+        if (tableTemplates.getSelectedRow() == -1) {
+            return;
+        }
+
+        final Template t = ca.getTemplates().get(tableTemplates.getSelectedRow());
+        if (t.isEnabled()) {
+            return;
+        }
+        ca.setTemplateEnable(t, true);
+        unsaved.set(true);
+    }
+
+    /**
+     * EFFECTS: Disable a template.
+     * MODIFIES: this
+     */
+    private void onDisableTemplate(ActionEvent ev) {
+        if (tableTemplates.getSelectedRow() == -1) {
+            return;
+        }
+
+        final Template t = ca.getTemplates().get(tableTemplates.getSelectedRow());
+        if (!t.isEnabled()) {
+            return;
+        }
+        ca.setTemplateEnable(t, false);
+        unsaved.set(true);
+    }
+
+    /**
+     * EFFECTS: Delete a template.
+     * MODIFIES: this
+     */
+    private void onDeleteTemplate(ActionEvent ev) {
+        if (tableTemplates.getSelectedRow() == -1) {
+            return;
+        }
+
+        final Template t = ca.getTemplates().get(tableTemplates.getSelectedRow());
+        ca.removeTemplate(t);
+        unsaved.set(true);
+    }
+
+    /**
+     * EFFECTS: Save the selected cert as a DER binary.
+     * MODIFIES: this
+     */
+    private void onExportCert(ActionEvent ev) {
+        if (tableCerts.getSelectedRow() == -1) {
+            return;
+        }
+
+        final Certificate c = ca.getSigned().get(tableCerts.getSelectedRow());
+        final Path p = chooseFile(rootPanel, "DER binary (*.crt)", "crt");
+        if (p == null) {
+            return;
+        }
+        try {
+            final OutputStream fd = Files.newOutputStream(p,
+                    StandardOpenOption.WRITE, StandardOpenOption.TRUNCATE_EXISTING, StandardOpenOption.CREATE);
+            fd.write(Utils.byteToByte(c.encodeDER()));
+            fd.close();
+        } catch (IOException e) {
+            alert(rootPanel, "Export certificate", e);
+        }
+    }
+
+    /**
+     * EFFECTS: Show revocation dialog for the selected cert. Save enforced.
+     * MODIFIES: this
+     */
+    private void onRevokeCert(ActionEvent ev) {
+        if (tableCerts.getSelectedRow() == -1) {
+            return;
+        }
+
+        final Certificate c = ca.getSigned().get(tableCerts.getSelectedRow());
+        if (ca.getRevoked().stream().anyMatch(r ->
+                r.getSerialNumber().getLong() == c.getCertificate().getSerialNumber().getLong())) {
+            return;
+        }
+        final RevokeDialog diag = new RevokeDialog(c);
+        diag.pack();
+        diag.setLocationRelativeTo(this);
+        diag.setVisible(true);
+
+        final RevokedCertificate res = diag.getRes();
+        if (res == null) {
+            return;
+        }
+
+        ca.revoke(res);
+        onSave(null);
+    }
+
+    /**
+     * EFFECTS: Sign a CRL and save to disk. Save enforced.
+     * MODIFIES: this
+     * REQUIRES: Proper private key and CA cert installed.
+     */
+    private void onCRL(ActionEvent ev) {
+        final Path p = chooseFile(rootPanel, "DER CRL (*.crl)", "crl");
+        if (p == null) {
+            return;
+        }
+        try {
+            final OutputStream fd = Files.newOutputStream(p,
+                    StandardOpenOption.WRITE,
+                    StandardOpenOption.TRUNCATE_EXISTING,
+                    StandardOpenOption.CREATE);
+            final CertificateList crl = ca.signCRL();
+            fd.write(Utils.byteToByte(crl.encodeDER()));
+            fd.close();
+            onSave(null);
+        } catch (IOException | SignatureException | InvalidKeyException | NoSuchAlgorithmException e) {
+            alert(rootPanel, "Sign CRL", e);
+        }
+    }
+
+    /**
+     * EFFECTS: Pick a CSR, show issue dialog, sign cert. Save enforced.
+     * MODIFIES: this
+     * REQUIRES: Proper private key / CA is installed.
+     */
+    private void onIssue(ActionEvent ev) {
+        if (ca.getTemplates().stream().noneMatch(Template::isEnabled)) {
+            alert(rootPanel, "Issue new certificate", "No enabled templates.");
+            return;
+        }
+        final Path p = chooseFile(rootPanel, "DER CSR (*.csr, *.pem)", "csr", "pem");
+        if (p == null) {
+            return;
+        }
+        try {
+            CertificationRequest csr = new CertificationRequest(new BytesReader(UIUtils.openDERorPEM(p,
+                    "CERTIFICATE REQUEST")), false);
+            final IssueDialog diag = new IssueDialog(csr, ca.getTemplates());
+            diag.setLocationRelativeTo(this);
+            diag.setVisible(true);
+            final Template res = diag.getRes();
+            if (res == null) {
+                return;
+            }
+            ca.signCert(csr.getCertificationRequestInfo(), res);
+            onSave(null);
+        } catch (IOException | ParseException | NoSuchAlgorithmException | SignatureException | InvalidKeyException e) {
+            alert(rootPanel, "Issue new certificate", e);
+        }
+    }
+
+    /**
+     * EFFECTS: Show the new template dialog and add a template.
+     * MODIFIES: this
+     */
+    private void onNewTemplate(ActionEvent ev) {
+        final TemplateEditDialog diag = new TemplateEditDialog(temp ->
+                ca.getTemplates().stream().anyMatch(t -> t.getName().equals(temp)));
+        diag.pack();
+        diag.setLocationRelativeTo(this);
+        diag.setVisible(true);
+        final Template res = diag.getRes();
+        if (res == null) {
+            return;
+        }
+        ca.addTemplate(res);
+        unsaved.set(true);
+    }
+}
diff --git a/src/main/ui/gui/RevokeDialog.java b/src/main/ui/gui/RevokeDialog.java
new file mode 100644
index 0000000..9cebc74
--- /dev/null
+++ b/src/main/ui/gui/RevokeDialog.java
@@ -0,0 +1,184 @@
+package ui.gui;
+
+import model.asn1.ASN1Object;
+import model.asn1.UtcTime;
+import model.pki.cert.Certificate;
+import model.pki.crl.Reason;
+import model.pki.crl.RevokedCertificate;
+import ui.gui.widgets.GCBuilder;
+import ui.gui.widgets.UIUtils;
+
+import javax.swing.*;
+import java.awt.*;
+import java.awt.event.ActionEvent;
+import java.awt.event.KeyEvent;
+import java.awt.event.WindowAdapter;
+import java.awt.event.WindowEvent;
+import java.time.ZoneId;
+import java.time.ZonedDateTime;
+import java.time.format.DateTimeFormatter;
+import java.time.format.DateTimeParseException;
+import java.util.Arrays;
+
+import static java.awt.GridBagConstraints.HORIZONTAL;
+import static java.awt.GridBagConstraints.WEST;
+import static ui.gui.widgets.UIUtils.alert;
+
+/**
+ * A dialog that presents user with cert info, revocation reason, and revocation time.
+ * +----------------------------+
+ * |Revoking: CN=xyz (Serial: 1)|
+ * |Reason:   (Drop Down)       |
+ * |Time:     (ISO-8601 text)   |
+ * |                            |
+ * |               Revoke Cancel|
+ * +----------------------------+
+ */
+public class RevokeDialog extends JDialog {
+    /**
+     * ISO8601
+     */
+    private static final DateTimeFormatter DATE_FORMAT = DateTimeFormatter.ISO_OFFSET_DATE_TIME;
+
+    /**
+     * The incoming certificate.
+     */
+    private final Certificate crt;
+
+    /**
+     * The result.
+     */
+    private RevokedCertificate res;
+
+
+    /**
+     * Root pane
+     */
+    private JPanel contentPane;
+
+    /**
+     * OK button
+     */
+    private JButton buttonOK;
+
+    /**
+     * Cancel button
+     */
+    private JButton buttonCancel;
+
+    /**
+     * Reason
+     */
+    private JComboBox<String> comboBoxReason;
+
+    /**
+     * Subject (not editable)
+     */
+    private JTextField textFieldSubject;
+
+    /**
+     * Time
+     */
+    private JFormattedTextField formattedTextFieldTime;
+
+    /**
+     * EFFECTS: Init GUI with the given cert.
+     */
+    public RevokeDialog(Certificate crt) {
+        this.crt = crt;
+
+        contentPane = new JPanel();
+        contentPane.setLayout(new BoxLayout(contentPane, BoxLayout.PAGE_AXIS));
+        contentPane.setBorder(BorderFactory.createEmptyBorder(8, 8, 8, 8));
+        contentPane.add(renderForm());
+
+        contentPane.add(UIUtils.createActionsPane(buttonOK = new JButton("Revoke"),
+                        buttonCancel = new JButton("Cancel")));
+        buttonOK.addActionListener(this::onOK);
+        buttonCancel.addActionListener(this::onCancel);
+
+        setContentPane(contentPane);
+        setModal(true);
+        getRootPane().setDefaultButton(buttonOK);
+        setDefaultCloseOperation(DO_NOTHING_ON_CLOSE);
+
+        setTitle("Revoke certificate");
+
+        addWindowListener(new WindowAdapter() {
+            public void windowClosing(WindowEvent e) {
+                onCancel(null);
+            }
+        });
+
+        contentPane.registerKeyboardAction(this::onCancel,
+                KeyStroke.getKeyStroke(KeyEvent.VK_ESCAPE, 0),
+                JComponent.WHEN_ANCESTOR_OF_FOCUSED_COMPONENT);
+    }
+
+    /**
+     * EFFECTS: Init GUI.
+     * MODIFIES: this
+     */
+    private JPanel renderForm() {
+        final JPanel panelForm = new JPanel();
+        panelForm.setLayout(new GridBagLayout());
+
+        panelForm.add(new JLabel("Revoking: "), new GCBuilder().anchor(WEST).build());
+        panelForm.add(new JLabel("Reason: "), new GCBuilder().gridY(1).anchor(WEST).build());
+        panelForm.add(new JLabel("Time: "), new GCBuilder().gridY(2).anchor(WEST).build());
+
+        textFieldSubject = new JTextField(String.format("%s (Serial: %d)",
+                crt.getCertificate().getSubject().toString(), crt.getCertificate().getSerialNumber().getLong()));
+        textFieldSubject.setEditable(false);
+        panelForm.add(textFieldSubject, new GCBuilder().gridX(1).anchor(WEST).fill(HORIZONTAL).build());
+
+        comboBoxReason = new JComboBox<>(Arrays.stream(Reason.values()).map(Enum::toString).toArray(String[]::new));
+        panelForm.add(comboBoxReason, new GCBuilder().gridXY(1, 1).anchor(WEST).fill(HORIZONTAL).build());
+
+        formattedTextFieldTime = new JFormattedTextField(DATE_FORMAT.toFormat());
+        formattedTextFieldTime.setText(ZonedDateTime.now().format(DATE_FORMAT));
+        panelForm.add(formattedTextFieldTime, new GCBuilder().gridXY(1, 2).anchor(WEST).fill(HORIZONTAL).build());
+
+        panelForm.add(new JPanel(), new GCBuilder().gridXY(1, 3).expandXY().fill(HORIZONTAL).build());
+        return panelForm;
+    }
+
+    /**
+     * EFFECTS: Validate form, set result, and close dialog.
+     *          Time must be a valid ISO-8601 string with offset, and it will be converted into UTC.
+     *          Reason must be supported.
+     * MODIFIES: this
+     */
+    private void onOK(ActionEvent ev) {
+        try {
+            res = new RevokedCertificate(ASN1Object.TAG_SEQUENCE, null,
+                    crt.getCertificate().getSerialNumber(),
+                    new UtcTime(UtcTime.TAG, null,
+                            ZonedDateTime.parse(formattedTextFieldTime.getText(), DATE_FORMAT)
+                                    .withZoneSameInstant(ZoneId.of("UTC"))),
+                    Reason.valueOf(comboBoxReason.getSelectedItem().toString()));
+            dispose();
+        } catch (DateTimeParseException e) {
+            alert(rootPane, "Revoke certificate", "Invalid time: " + formattedTextFieldTime.getText()
+                    + ". It must be a valid ISO8601 time with offset, like '1919-08-10T11:45:14+09:00'.");
+        } catch (IllegalArgumentException e) {
+            alert(rootPane, "Revoke certificate", "Invalid reason.");
+        }
+    }
+
+    /**
+     * EFFECTS: Clear the result and close dialog.
+     * MODIFIES: this
+     */
+    private void onCancel(ActionEvent ev) {
+        res = null;
+        dispose();
+    }
+
+    /**
+     * EFFECTS: Get result.
+     */
+    public RevokedCertificate getRes() {
+        return res;
+    }
+}
diff --git a/src/main/ui/gui/TemplateEditDialog.java b/src/main/ui/gui/TemplateEditDialog.java
new file mode 100644
index 0000000..557d207
--- /dev/null
+++ b/src/main/ui/gui/TemplateEditDialog.java
@@ -0,0 +1,73 @@
+package ui.gui;
+
+import model.asn1.exceptions.ParseException;
+import model.ca.Template;
+import model.x501.Name;
+import ui.gui.widgets.CertEditDialog;
+
+import javax.swing.*;
+import java.awt.event.ActionEvent;
+import java.util.function.Function;
+
+import static ui.gui.widgets.UIUtils.alert;
+
+/**
+ * A dialog that allows users to input template name, subject, and validity.
+ */
+public class TemplateEditDialog extends CertEditDialog<Template> {
+    /**
+     * Callback function to check for name conflict.
+     */
+    private final Function<String, Boolean> dupDetector;
+
+    /**
+     * Text field for name.
+     */
+    private JTextField templateComponent;
+
+    /**
+     * EFFECTS: Init UI, title = New Template, OK button = Add, set dup detector.
+     */
+    public TemplateEditDialog(Function<String, Boolean> dupDetector) {
+        super();
+        this.dupDetector = dupDetector;
+        setTitle("New template");
+        buttonOK.setText("Add");
+    }
+
+    /**
+     * EFFECTS: Initialize the subject text field with JTextField.
+     * MODIFIES: this
+     */
+    @Override
+    protected JComponent createTemplateComponent() {
+        return templateComponent = new JTextField();
+    }
+
+    /**
+     * EFFECTS: Validate the form, set the result, and close the dialog.
+     *          Name must not be null; Name must not conflict; Subject must be valid.
+     * MODIFIES: this
+     */
+    @Override
+    protected void onOK(ActionEvent ev) {
+        if (templateComponent.getText().isEmpty()) {
+            alert(rootPane, getTitle(), "The template name must not be empty.");
+            return;
+        }
+        if (dupDetector.apply(templateComponent.getText())) {
+            alert(rootPane, getTitle(), "The template exists.");
+            return;
+        }
+
+        try {
+            res = new Template(templateComponent.getText(),
+                    false,
+                    textFieldSubject.getText().isBlank() ? null : Name.parseString(textFieldSubject.getText()),
+                    (Integer) spinnerValidity.getValue());
+            dispose();
+        } catch (ParseException e) {
+            alert(rootPane, getTitle(), e);
+        }
+    }
+}
diff --git a/src/main/ui/gui/widgets/CertEditDialog.java b/src/main/ui/gui/widgets/CertEditDialog.java
new file mode 100644
index 0000000..6c440a3
--- /dev/null
+++ b/src/main/ui/gui/widgets/CertEditDialog.java
@@ -0,0 +1,108 @@
+package ui.gui.widgets;
+
+import javax.swing.*;
+import java.awt.*;
+import java.awt.event.ActionEvent;
+import java.awt.event.KeyEvent;
+import java.awt.event.WindowAdapter;
+import java.awt.event.WindowEvent;
+
+import static java.awt.GridBagConstraints.HORIZONTAL;
+import static java.awt.GridBagConstraints.WEST;
+import static ui.gui.widgets.UIUtils.btn;
+
+/**
+ * A common dialog for cert / template editing. It will close upon Esc or Cancel.
+ * +---------------------------++---------------------------++---------------------------+
+ * |  Dialog                 X ||  New Template           X ||  Issue new certificate  X |
+ * |                           ||                           ||                           |
+ * |Template:          (TBD)   ||Template:         _________||Template:       (Drop down)|
+ * |Subject:          _________||Subject:          _________||Subject:         _________ |
+ * |Validity (Days):  (Spinner)||Validity (Days):  (Spinner)||Validity (Days):  (Spinner)|
+ * |                           ||                           ||                           |
+ * |              Button Cancel||                 Add Cancel||               Issue Cancel|
+ * +---------------------------++---------------------------++---------------------------+
+ */
+public abstract class CertEditDialog<T> extends JDialog {
+    /**
+     * The result.
+     */
+    protected T res;
+
+    /**
+     * Root pane.
+     */
+    protected JPanel contentPane = new JPanel();
+    protected JButton buttonOK = UIUtils.btn("", this::onOK);
+    protected JTextField textFieldSubject = new JTextField();
+    protected JSpinner spinnerValidity =
+            new JSpinner(new SpinnerNumberModel(60, 1, null, 0));
+
+    /**
+     * EFFECTS: Render the dialog, leaving title and OK button text blank.
+     */
+    public CertEditDialog() {
+        contentPane.setLayout(new BoxLayout(contentPane, BoxLayout.PAGE_AXIS));
+        contentPane.setBorder(BorderFactory.createEmptyBorder(8, 8, 8, 8));
+        contentPane.add(renderForm());
+
+        contentPane.add(UIUtils.createActionsPane(buttonOK, UIUtils.btn("Cancel", this::onCancel)));
+
+        setContentPane(contentPane);
+        setModal(true);
+        getRootPane().setDefaultButton(buttonOK);
+        setDefaultCloseOperation(DO_NOTHING_ON_CLOSE);
+
+        addWindowListener(new WindowAdapter() {
+            public void windowClosing(WindowEvent e) {
+                onCancel(null);
+            }
+        });
+
+        contentPane.registerKeyboardAction(this::onCancel,
+                KeyStroke.getKeyStroke(KeyEvent.VK_ESCAPE, 0),
+                JComponent.WHEN_ANCESTOR_OF_FOCUSED_COMPONENT);
+    }
+
+    /**
+     * EFFECTS: Render the form.
+     */
+    private JPanel renderForm() {
+        final JPanel panelForm = new JPanel(new GridBagLayout());
+        panelForm.add(new JLabel("Template: "), new GCBuilder().anchor(WEST).build());
+        panelForm.add(new JLabel("Subject: "), new GCBuilder().gridY(1).anchor(WEST).build());
+        panelForm.add(new JLabel("Validity (Days): "), new GCBuilder().gridY(2).anchor(WEST).build());
+        panelForm.add(createTemplateComponent(), new GCBuilder().gridXY(1, 0).anchor(WEST)
+                .fill(HORIZONTAL).build());
+        panelForm.add(textFieldSubject, new GCBuilder().gridXY(1, 1).anchor(WEST).fill(HORIZONTAL).build());
+        panelForm.add(spinnerValidity, new GCBuilder().gridXY(1, 2).anchor(WEST).fill(HORIZONTAL).build());
+        panelForm.add(new JPanel(), new GCBuilder().gridXY(1, 3).expandXY().fill(HORIZONTAL).build());
+        return panelForm;
+    }
+
+    /**
+     * EFFECTS: Create the component for subject.
+     */
+    protected abstract JComponent createTemplateComponent();
+
+    /**
+     * EFFECTS: Handle OK.
+     */
+    protected abstract void onOK(ActionEvent ev);
+
+    /**
+     * EFFECTS: Handle cancel: clear result and close dialog.
+     * MODIFIES: this
+     */
+    private void onCancel(ActionEvent ev) {
+        res = null;
+        dispose();
+    }
+
+    /**
+     * EFFECTS: Get the result.
+     */
+    public T getRes() {
+        return res;
+    }
+}
diff --git a/src/main/ui/gui/widgets/CertTableModel.java b/src/main/ui/gui/widgets/CertTableModel.java
new file mode 100644
index 0000000..f10d621
--- /dev/null
+++ b/src/main/ui/gui/widgets/CertTableModel.java
@@ -0,0 +1,129 @@
+package ui.gui.widgets;
+
+import model.ca.CertificationAuthority;
+import model.pki.cert.Certificate;
+import model.pki.crl.RevokedCertificate;
+
+import javax.swing.*;
+import javax.swing.table.AbstractTableModel;
+import java.time.format.DateTimeFormatter;
+import java.util.List;
+
+/**
+ * Table model that displays issued certificates.
+ */
+public class CertTableModel extends AbstractTableModel {
+    /**
+     * Valid certificate icon.
+     */
+    private static final ImageIcon ICON_OK =
+            new ImageIcon(CertTableModel.class.getResource("/verified.png"));
+
+    /**
+     * Revoked certificate icon (same as toolbar revoke icon).
+     */
+    private static final ImageIcon ICON_REVOKED =
+            new ImageIcon(CertTableModel.class.getResource("/deletetest.png"));
+
+    /**
+     * Columns
+     */
+    private static final String[] COLS = new String[] {
+            "", // Icon
+            "Serial",
+            "Subject",
+            "Signed",
+            "Expires"
+    };
+
+    /**
+     * Pointer to {@link CertificationAuthority#getSigned()}
+     */
+    private List<Certificate> ptrData;
+
+    /**
+     * Pointer to {@link CertificationAuthority#getRevoked()}
+     */
+    private List<RevokedCertificate> ptrRevokedData;
+
+    /**
+     * EFFECTS: Set pointer to certs
+     * MODIFIES: this
+     */
+    public void setPtrData(List<Certificate> ptrData) {
+        this.ptrData = ptrData;
+    }
+
+    /**
+     * EFFECTS: Set pointer to revoked
+     * MODIFIES: this
+     */
+    public void setPtrRevokedData(List<RevokedCertificate> ptrRevokedData) {
+        this.ptrRevokedData = ptrRevokedData;
+    }
+
+    /**
+     * EFFECTS: Count rows.
+     */
+    @Override
+    public int getRowCount() {
+        return ptrData == null ? 0 : ptrData.size();
+    }
+
+    /**
+     * EFFECTS: Count columns.
+     */
+    @Override
+    public int getColumnCount() {
+        return COLS.length;
+    }
+
+    /**
+     * EFFECTS: Get column name.
+     * REQUIRES: column in [9, getColumnCount())
+     */
+    @Override
+    public String getColumnName(int column) {
+        return COLS[column];
+    }
+
+    /**
+     * EFFECTS: Return the value for a cell:
+     *          ImageIcon (Valid / Revoked)
+     *          String (Serial number)
+     *          String (Subject)
+     *          String (NotBefore)
+     *          String (NotAfter)
+     *          Throws {@link IllegalArgumentException} if columnIndex is not in 0 ~ 4
+     * REQUIRES: rowIndex must in range.
+     */
+    @Override
+    public Object getValueAt(int rowIndex, int columnIndex) {
+        final Certificate e = ptrData.get(rowIndex);
+        switch (columnIndex) {
+            case 0: return ptrRevokedData.stream().anyMatch(r ->
+                    r.getSerialNumber().getLong() == e.getCertificate().getSerialNumber().getLong()
+            ) ? ICON_REVOKED : ICON_OK;
+            case 1: return e.getCertificate().getSerialNumber().getLong();
+            case 2: return e.getCertificate().getSubject().toString();
+            case 3:
+                return e.getCertificate().getValidity().getNotBefore().getTimestamp()
+                        .format(DateTimeFormatter.ISO_LOCAL_DATE_TIME);
+            case 4:
+                return e.getCertificate().getValidity().getNotAfter().getTimestamp()
+                        .format(DateTimeFormatter.ISO_LOCAL_DATE_TIME);
+            default: throw new IllegalArgumentException();
+        }
+    }
+
+    /**
+     * EFFECTS: Return ImageIcon for 0, String otherwise.
+     */
+    @Override
+    public Class<?> getColumnClass(int columnIndex) {
+        switch (columnIndex) {
+            case 0: return ImageIcon.class;
+            default: return String.class;
+        }
+    }
+}
diff --git a/src/main/ui/gui/widgets/GCBuilder.java b/src/main/ui/gui/widgets/GCBuilder.java
new file mode 100644
index 0000000..a571aab
--- /dev/null
+++ b/src/main/ui/gui/widgets/GCBuilder.java
@@ -0,0 +1,213 @@
+package ui.gui.widgets;
+
+import java.awt.*;
+
+/**
+ * A builder for {@link GridBagConstraints}.
+ */
+public class GCBuilder {
+    /**
+     * Grix X and Y, defaults to {@link GridBagConstraints#RELATIVE}
+     */
+    private int gridX = GridBagConstraints.RELATIVE;
+
+    private int gridY = GridBagConstraints.RELATIVE;
+
+    /**
+     * Weight X and Y, [0.0, 1.0], defaults to 0.0
+     */
+    private double weightX = 0.0;
+
+    private double weightY = 0.0;
+
+    /**
+     * Anchor, defaults to {@link GridBagConstraints#CENTER}
+     */
+    private int anchor = GridBagConstraints.CENTER;
+
+    /**
+     * How to stretch the component, defaults to {@link GridBagConstraints#NONE}
+     */
+    private int fill = GridBagConstraints.NONE;
+
+    /**
+     * Insects in pixels.
+     */
+    private int insectTop = 0;
+
+    private int insectLeft = 0;
+
+    private int insectRight = 0;
+
+    private int insectBottom = 0;
+
+    /**
+     * EFFECTS: Build the {@link GridBagConstraints} based on parameters.
+     * Grid width, grid height, ipad X, ipad Y will be 1, 1, 0, 0.
+     */
+    public GridBagConstraints build() {
+        return new GridBagConstraints(gridX, gridY,
+                1, 1,
+                weightX, weightY,
+                anchor, fill,
+                new Insets(insectTop, insectLeft, insectBottom, insectRight),
+                0, 0);
+    }
+
+    /**
+     * EFFECTS: Set grid X and Y.
+     * REQUIRES: > 0
+     * MODIFIES: this
+     */
+    public GCBuilder gridXY(int gridX, int gridY) {
+        return this.gridX(gridX).gridY(gridY);
+    }
+
+    /**
+     * EFFECTS: Set grid X.
+     * REQUIRES: > 0
+     * MODIFIES: this
+     */
+    public GCBuilder gridX(int gridX) {
+        this.gridX = gridX;
+        return this;
+    }
+
+    /**
+     * EFFECTS: Set grid Y.
+     * REQUIRES: > 0
+     * MODIFIES: this
+     */
+    public GCBuilder gridY(int gridY) {
+        this.gridY = gridY;
+        return this;
+    }
+
+    /**
+     * EFFECTS: Set weight X and Y.
+     * REQUIRES: [0.0, 1.0]
+     * MODIFIES: this
+     */
+    public GCBuilder weightXY(double weightX, double weightY) {
+        return this.weightX(weightX).weightY(weightY);
+    }
+
+    /**
+     * EFFECTS: Set weight X and Y to 1.0
+     * MODIFIES: this
+     */
+    public GCBuilder expandXY() {
+        return this.expandX().expandY();
+    }
+
+    /**
+     * EFFECTS: Set weight X to 1.0
+     * MODIFIES: this
+     */
+    public GCBuilder expandX() {
+        return this.weightX(1.0);
+    }
+
+    /**
+     * EFFECTS: Set weight X to 1.0
+     * MODIFIES: this
+     */
+    public GCBuilder weightX(double weightX) {
+        this.weightX = weightX;
+        return this;
+    }
+
+    /**
+     * EFFECTS: Set weight Y to 1.0
+     * MODIFIES: this
+     */
+    public GCBuilder expandY() {
+        return this.weightY(1.0);
+    }
+
+    /**
+     * EFFECTS: Set weight X to 1.0
+     * MODIFIES: this
+     */
+    public GCBuilder weightY(double weightY) {
+        this.weightY = weightY;
+        return this;
+    }
+
+    /**
+     * EFFECTS: Set anchor.
+     * REQUIRES: anchor in {@link GridBagConstraints} constants.
+     * MODIFIES: this
+     */
+    public GCBuilder anchor(int anchor) {
+        this.anchor = anchor;
+        return this;
+    }
+
+    /**
+     * EFFECTS: Set fill.
+     * REQUIRES: fill in {@link GridBagConstraints} constants.
+     * MODIFIES: this
+     */
+    public GCBuilder fill(int fill) {
+        this.fill = fill;
+        return this;
+    }
+
+    /**
+     * EFFECTS: Set insects to be 8, 8, 8, 8
+     * MODIFIES: this
+     */
+    public GCBuilder marginInsects() {
+        return this.insects(8, 8, 8, 8);
+    }
+
+    /**
+     * EFFECTS: Set insects.
+     * REQUIRES: >= 0
+     * MODIFIES: this
+     */
+    public GCBuilder insects(int top, int left, int bottom, int right) {
+        return this.insectTop(top).insectLeft(left).insectBottom(bottom).insectRight(right);
+    }
+
+    /**
+     * EFFECTS: Set top insect
+     * REQUIRES: >= 0
+     * MODIFIES: this
+     */
+    public GCBuilder insectTop(int insectTop) {
+        this.insectTop = insectTop;
+        return this;
+    }
+
+    /**
+     * EFFECTS: Set left insect
+     * REQUIRES: >= 0
+     * MODIFIES: this
+     */
+    public GCBuilder insectLeft(int insectLeft) {
+        this.insectLeft = insectLeft;
+        return this;
+    }
+
+    /**
+     * EFFECTS: Set right insect
+     * REQUIRES: >= 0
+     * MODIFIES: this
+     */
+    public GCBuilder insectRight(int insectRight) {
+        this.insectRight = insectRight;
+        return this;
+    }
+
+    /**
+     * EFFECTS: Set bottom insect
+     * REQUIRES: >= 0
+     * MODIFIES: this
+     */
+    public GCBuilder insectBottom(int insectBottom) {
+        this.insectBottom = insectBottom;
+        return this;
+    }
+}
diff --git a/src/main/ui/gui/widgets/LogTableModel.java b/src/main/ui/gui/widgets/LogTableModel.java
new file mode 100644
index 0000000..a7b52ac
--- /dev/null
+++ b/src/main/ui/gui/widgets/LogTableModel.java
@@ -0,0 +1,79 @@
+package ui.gui.widgets;
+
+import model.ca.AuditLogEntry;
+import model.ca.CertificationAuthority;
+
+import javax.swing.table.AbstractTableModel;
+import java.time.format.DateTimeFormatter;
+import java.util.List;
+
+/**
+ * Table model that displays audit logs.
+ */
+public class LogTableModel extends AbstractTableModel {
+    /**
+     * Columns
+     */
+    private static final String[] COLS = new String[] {
+            "Time",
+            "Operator",
+            "Action"
+    };
+
+    /**
+     * Pointer to the {@link CertificationAuthority#getLogs()}.
+     */
+    private List<AuditLogEntry> ptrData;
+
+    /**
+     * EFFECTS: Set the pointer to templates
+     * MODIFIES: this
+     */
+    public void setPtrData(List<AuditLogEntry> ptrData) {
+        this.ptrData = ptrData;
+    }
+
+    /**
+     * EFFECT: Return number of rows.
+     */
+    @Override
+    public int getRowCount() {
+        return ptrData == null ? 0 : ptrData.size();
+    }
+
+    /**
+     * EFFECT: Return number of columns.
+     */
+    @Override
+    public int getColumnCount() {
+        return COLS.length;
+    }
+
+    /**
+     * EFFECTS: Get column name.
+     * REQUIRES: column in [9, getColumnCount())
+     */
+    @Override
+    public String getColumnName(int column) {
+        return COLS[column];
+    }
+
+    /**
+     * EFFECTS: Return the value for a cell:
+     *          String (Time)
+     *          String (Operator)
+     *          String (Action)
+     *          Throws {@link IllegalArgumentException} if columnIndex is not in 0 ~ 2
+     * REQUIRES: rowIndex must in range.
+     */
+    @Override
+    public Object getValueAt(int rowIndex, int columnIndex) {
+        final AuditLogEntry e = ptrData.get(rowIndex);
+        switch (columnIndex) {
+            case 0: return e.getTime().format(DateTimeFormatter.ISO_LOCAL_DATE_TIME);
+            case 1: return e.getUser();
+            case 2: return e.getAction();
+            default: throw new IllegalArgumentException();
+        }
+    }
+}
diff --git a/src/main/ui/gui/widgets/QRPanel.java b/src/main/ui/gui/widgets/QRPanel.java
new file mode 100644
index 0000000..ebd70af
--- /dev/null
+++ b/src/main/ui/gui/widgets/QRPanel.java
@@ -0,0 +1,77 @@
+package ui.gui.widgets;
+
+import com.google.zxing.BarcodeFormat;
+import com.google.zxing.WriterException;
+import com.google.zxing.common.BitMatrix;
+import com.google.zxing.qrcode.QRCodeWriter;
+
+import javax.swing.*;
+import java.awt.*;
+import java.util.Collections;
+
+import static com.google.zxing.EncodeHintType.ERROR_CORRECTION;
+import static com.google.zxing.qrcode.decoder.ErrorCorrectionLevel.L;
+
+/**
+ * A fixed-size panel displaying a QR code.
+ */
+public class QRPanel extends JPanel {
+    private final int size;
+
+    private BitMatrix data;
+
+    /**
+     * EFFECTS: Init with the specific rectangular size. Min size = max size = preferred size.
+     */
+    public QRPanel(int size) {
+        super();
+        setSize(new Dimension(size, size));
+        setMaximumSize(new Dimension(size, size));
+        setMinimumSize(new Dimension(size, size));
+        setPreferredSize(new Dimension(size, size));
+        this.size = size;
+    }
+
+    /**
+     * EFFECTS: Draw the QR code. Leave white if no data is set.
+     * MODIFIES: this
+     */
+    @Override
+    protected void paintComponent(Graphics graphics) {
+        super.paintComponent(graphics);
+        graphics.setColor(Color.WHITE);
+        graphics.fillRect(0, 0, size, size);
+
+        if (data == null) {
+            return;
+        }
+
+        graphics.setColor(Color.BLACK);
+        for (int i = 0; i < size; i++) {
+            for (int j = 0; j < size; j++) {
+                if (data.get(i, j)) {
+                    graphics.fillRect(i, j, 1, 1);
+                }
+            }
+        }
+    }
+
+    /**
+     * EFFECTS: Set data and repaint. Nullable.
+     * MODIFIES: this
+     */
+    public void setData(String data) {
+        if (data == null) {
+            this.data = null;
+            invalidate();
+            return;
+        }
+        try {
+            this.data = new QRCodeWriter().encode(data, BarcodeFormat.QR_CODE, size, size,
+                    Collections.singletonMap(ERROR_CORRECTION, L));
+        } catch (WriterException e) {
+            e.printStackTrace();
+        }
+        invalidate();
+    }
+}
diff --git a/src/main/ui/gui/widgets/TemplateTableModel.java b/src/main/ui/gui/widgets/TemplateTableModel.java
new file mode 100644
index 0000000..de23b54
--- /dev/null
+++ b/src/main/ui/gui/widgets/TemplateTableModel.java
@@ -0,0 +1,105 @@
+package ui.gui.widgets;
+
+import model.ca.CertificationAuthority;
+import model.ca.Template;
+
+import javax.swing.*;
+import javax.swing.table.AbstractTableModel;
+import java.util.List;
+
+/**
+ * Table model that displays templates.
+ */
+public class TemplateTableModel extends AbstractTableModel {
+    /**
+     * Template enabled icon, same as toolbar enable icon.
+     */
+    private static final ImageIcon ICON_ENABLED =
+            new ImageIcon(TemplateTableModel.class.getResource("/enable.png"));
+
+    /**
+     * Template disbled icon, same as toolbar enable icon.
+     */
+    private static final ImageIcon ICON_DISABLED =
+            new ImageIcon(TemplateTableModel.class.getResource("/disable.png"));
+
+    /**
+     * Columns
+     */
+    private static final String[] COLS = new String[] {
+            "", // Icon
+            "Name",
+            "Subject",
+            "Validity"
+    };
+
+    /**
+     * Pointer to the {@link CertificationAuthority#getTemplates()}.
+     */
+    private List<Template> ptrData;
+
+    /**
+     * EFFECTS: Set the pointer to templates
+     * MODIFIES: this
+     */
+    public void setPtrData(List<Template> ptrData) {
+        this.ptrData = ptrData;
+    }
+
+    /**
+     * EFFECT: Return number of rows.
+     * REQUIRES: column in [9, getColumnCount())
+     */
+    @Override
+    public int getRowCount() {
+        return ptrData == null ? 0 : ptrData.size();
+    }
+
+    /**
+     * EFFECT: Return number of rows.
+     */
+    @Override
+    public int getColumnCount() {
+        return COLS.length;
+    }
+
+    /**
+     * EFFECTS: Get column name.
+     */
+    @Override
+    public String getColumnName(int column) {
+        return COLS[column];
+    }
+
+    /**
+     * EFFECTS: Return the value for a cell:
+     *          ImageIcon (Enabled / Disabled)
+     *          String (Name)
+     *          String (Subject or Not Set)
+     *          String (xx days)
+     *          Throws {@link IllegalArgumentException} if columnIndex is not in 0 ~ 3
+     * REQUIRES: rowIndex must in range.
+     */
+    @Override
+    public Object getValueAt(int rowIndex, int columnIndex) {
+        final Template e = ptrData.get(rowIndex);
+        switch (columnIndex) {
+            case 0: return e.isEnabled() ? ICON_ENABLED : ICON_DISABLED;
+            case 1: return e.getName();
+            case 2: return e.getSubject() == null ? "<Not Set>" : e.getSubject().toString();
+            case 3: return String.format("%d days", e.getValidity());
+            default: throw new IllegalArgumentException();
+        }
+    }
+
+    /**
+     * EFFECTS: Return ImageIcon for 0, String otherwise.
+     */
+    @Override
+    public Class<?> getColumnClass(int columnIndex) {
+        switch (columnIndex) {
+            case 0: return ImageIcon.class;
+            default: return String.class;
+        }
+    }
+}
diff --git a/src/main/ui/gui/widgets/UIUtils.java b/src/main/ui/gui/widgets/UIUtils.java
new file mode 100644
index 0000000..bb09a72
--- /dev/null
+++ b/src/main/ui/gui/widgets/UIUtils.java
@@ -0,0 +1,168 @@
+package ui.gui.widgets;
+
+import model.asn1.exceptions.ParseException;
+import ui.Utils;
+
+import javax.swing.*;
+import javax.swing.filechooser.FileNameExtensionFilter;
+import java.awt.*;
+import java.awt.event.ActionListener;
+import java.io.IOException;
+import java.io.InputStream;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.nio.file.StandardOpenOption;
+import java.util.stream.IntStream;
+
+import static java.awt.GridBagConstraints.BOTH;
+import static java.awt.GridBagConstraints.HORIZONTAL;
+import static javax.swing.JOptionPane.*;
+
+/**
+ * Useful utilities for building GUI.
+ */
+public class UIUtils {
+    /**
+     * EFFECTS: Create a horizontal actions pane:
+     * -----------------------------------------------------------
+     * |                 | Button1 | Button2 | Button3 | ButtonN |
+     * -----------------------------------------------------------
+     * REQUIRES: buttons != null
+     */
+    public static JPanel createActionsPane(JButton... buttons) {
+        final JPanel panelAct = new JPanel();
+        panelAct.setLayout(new GridBagLayout());
+        IntStream.range(0, buttons.length)
+                .forEach(i -> panelAct.add(buttons[i],
+                        new GCBuilder().gridXY(i + 1, 1).fill(HORIZONTAL).build()));
+        panelAct.add(new JPanel(), new GCBuilder().expandXY().fill(BOTH).build());
+        return panelAct;
+    }
+
+    /**
+     * EFFECTS: Show / hide default text for a card layout container.
+     * MODIFIES: cardLayoutPanel
+     * REQUIRES: cardLayoutPanel must have a card layout; it must have CardContent and CardDefault cards.
+     */
+    public static void setContentVisible(Container cardLayoutPanel, boolean showContent) {
+        switchTo(cardLayoutPanel, showContent ? "CardContent" : "CardDefault");
+    }
+
+    /**
+     * EFFECTS: Switch to the card for a card layout panel.
+     * MODIFIES: cardLayoutPanel
+     * REQUIRES: cardLayoutPanel must have a card layout; it must have "card" card.
+     */
+    public static void switchTo(Container cardLayoutPanel, String card) {
+        ((CardLayout) cardLayoutPanel.getLayout()).show(cardLayoutPanel, card);
+    }
+
+    /**
+     * EFFECTS: Show an error message based on {@link Throwable#getMessage()}
+     * REQUIRES: component must have a frame.
+     */
+    public static void alert(Component component, String title, Throwable e) {
+        alert(component, title, e.getMessage());
+    }
+
+    /**
+     * EFFECTS: Show an error message.
+     * REQUIRES: component must have a frame.
+     */
+    public static void alert(Component component, String title, String message) {
+        showMessageDialog(getFrameForComponent(component),
+                message,
+                title,
+                ERROR_MESSAGE);
+    }
+
+    /**
+     * EFFECTS: Show a file chooser with the given filter title and list of extensions. Starting from cwd.
+     * Return null if cancelled.
+     */
+    public static Path chooseFile(Component component, String filterTitle, String... extensions) {
+        final JFileChooser fc = new JFileChooser();
+        fc.setFileFilter(new FileNameExtensionFilter(filterTitle, extensions));
+        fc.setCurrentDirectory(Paths.get("").toAbsolutePath().toFile());
+        if (fc.showOpenDialog(getFrameForComponent(component)) == JFileChooser.APPROVE_OPTION) {
+            return fc.getSelectedFile().toPath();
+        }
+        return null;
+    }
+
+    /**
+     * EFFECTS: Create a JPanel with CardLayout that has CardDefault set to component and CardContent set to a JLabel
+     * with the default text.
+     */
+    public static JPanel defView(Component component, String defaultText) {
+        final JPanel panel = new JPanel();
+        panel.setLayout(new CardLayout(0, 0));
+
+        JLabel labelDefault = new JLabel(defaultText);
+        labelDefault.setHorizontalAlignment(0);
+        panel.add(labelDefault, "CardDefault");
+        panel.add(component, "CardContent");
+
+        return panel;
+    }
+
+    /**
+     * EFFECTS: Create a JScrollPane-wrapped JTable.
+     * MODIFIES: table
+     */
+    public static JScrollPane scrTbl(JTable table) {
+        final JScrollPane scrollPane = new JScrollPane();
+        table.setFillsViewportHeight(true);
+        scrollPane.setViewportView(table);
+        return scrollPane;
+    }
+
+    /**
+     * EFFECTS: Parse the given path and automatically determine if it is a DER binary or a PEM. Automatically decode
+     * PEM.
+     *      Throws {@link IOException} if it cannot be read.
+     *      Throws {@link ParseException} if the PEM is invalid.
+     */
+    public static Byte[] openDERorPEM(Path path, String tag) throws IOException, ParseException {
+        final InputStream fd = Files.newInputStream(path, StandardOpenOption.READ);
+        Byte[] bs = Utils.byteToByte(fd.readAllBytes());
+        fd.close();
+        if (bs.length < 1) {
+            throw new ParseException("Invalid file: too short");
+        }
+        if (bs[0] == '-') {
+            bs = Utils.parsePEM(bs, tag);
+        }
+        return bs;
+    }
+
+    /**
+     * EFFECTS: Create a button with the given label and click listener.
+     */
+    public static JButton btn(String string, ActionListener onClick) {
+        final JButton btn = new JButton(string);
+        btn.addActionListener(onClick);
+        return btn;
+    }
+
+    /**
+     * EFFECTS: Create a button with the given label, mnemonic, and click listener.
+     */
+    public static JButton btn(String string, char m, ActionListener onClick) {
+        final JButton btn = new JButton(string);
+        btn.setMnemonic(m);
+        btn.setDisplayedMnemonicIndex(0);
+        btn.addActionListener(onClick);
+        return btn;
+    }
+
+    /**
+     * EFFECTS: Create a button with the given label, mnemonic, icon, and click listener.
+     */
+    public static JButton btn(String string, String icon, ActionListener onClick) {
+        final JButton btn = new JButton(string, new ImageIcon(UIUtils.class.getResource("/" + icon)));
+        btn.addActionListener(onClick);
+        return btn;
+    }
+}
diff --git a/src/main/ui/tui/IssueScreen.java b/src/main/ui/tui/IssueScreen.java
new file mode 100644
index 0000000..26ceb02
--- /dev/null
+++ b/src/main/ui/tui/IssueScreen.java
@@ -0,0 +1,168 @@
+package ui.tui;
+
+import model.asn1.exceptions.ParseException;
+import model.ca.Template;
+import model.csr.CertificationRequest;
+import model.pki.cert.Certificate;
+import model.x501.Name;
+import ui.Utils;
+
+/**
+ * The screen that accepts a CSR and template and allows user to change its properties and issue.
+ */
+public class IssueScreen implements UIHandler {
+    private final JCA session;
+
+    private Template template;
+    private CertificationRequest incomingCSR;
+
+    /**
+     * EFFECTS: Init with the session.
+     */
+    public IssueScreen(JCA session) {
+        this.session = session;
+    }
+
+    /**
+     * EFFECTS: Set current template and CSR in use by args.
+     * REQUIRES: args.length = 2, args[0] instanceof CertificateRequest, args[1] instanceof Template
+     * MODIFIES: args[1]
+     */
+    @Override
+    public void enter(Object... args) {
+        this.incomingCSR = (CertificationRequest) args[0];
+        this.template = (Template) args[1];
+    }
+
+    /**
+     * EFFECTS: Print help.
+     */
+    @Override
+    public void help() {
+        System.out.print("show\tView the current certificate\n"
+                + "set\tSet properties or template\n"
+                + "commit\tIssue the certificate\n"
+                + "exit\tDiscard and go to main menu\n"
+                + "help\tPrint this message\n");
+    }
+
+    /**
+     * EFFECTS: Print pending cert info.
+     */
+    @Override
+    public void show() {
+        System.out.println("Requested Subject:\t" + incomingCSR.getCertificationRequestInfo().getSubject());
+        System.out.println("Subject:\t" + (template.getSubject() == null
+                ? incomingCSR.getCertificationRequestInfo().getSubject()
+                : template.getSubject()));
+        System.out.println("Template:\t" + template.getName());
+        System.out.println("Validity:\t" + template.getValidity() + " days");
+    }
+
+    /**
+     * EFFECTS: Issue the cert and log it.
+     * MODIFIES: session
+     */
+    @Override
+    public void commit() {
+        try {
+            Certificate certificate = session.getCa().signCert(incomingCSR.getCertificationRequestInfo(), template);
+            session.save();
+            System.out.println(Utils.toPEM(certificate.encodeDER(), "CERTIFICATE"));
+            session.setScreen(Screen.MAIN);
+        } catch (Throwable e) {
+            System.out.println(e.getMessage());
+        }
+    }
+
+    /**
+     * EFFECTS: Set or unset the subject.
+     * MODIFIES: this
+     */
+    private void handleIssueSetSubject(String val) {
+        try {
+            if (val == null) {
+                template = new Template(template.getName(), template.isEnabled(), (Name) null, template.getValidity());
+            } else {
+                template = new Template(template.getName(), template.isEnabled(), val, template.getValidity());
+            }
+        } catch (ParseException e) {
+            System.out.println(e.getMessage());
+        }
+    }
+
+    /**
+     * EFFECTS: Set or unset the validity.
+     * MODIFIES: this
+     */
+    private void handleIssueSetValidity(String val) {
+        if (val == null) {
+            System.out.println("Cannot unset validity");
+            return;
+        }
+        try {
+            long i = Long.parseLong(val);
+            if (i <= 0) {
+                System.out.println("Invalid validity days");
+                return;
+            }
+            template = new Template(template.getName(), template.isEnabled(), template.getSubject(), i);
+        } catch (NumberFormatException ignored) {
+            System.out.println("Invalid validity days");
+        }
+    }
+
+    /**
+     * EFFECTS: Handle the set command.
+     * MODIFIES: this
+     */
+    private void handleIssueSet(String... args) {
+        if (args.length != 2 && args.length != 3) {
+            System.out.println("Usage: set <key> <value>");
+            System.out.println("Supported keys: subject validity");
+            return;
+        }
+        String val = args.length == 3 ? args[2] : null;
+        switch (args[1]) {
+            case "subject":
+                handleIssueSetSubject(val);
+                break;
+            case "validity":
+                handleIssueSetValidity(val);
+                break;
+            default:
+                System.out.println("Unknown key");
+                break;
+        }
+    }
+
+    @Override
+    public void command(String... args) {
+        if (args[0].equals("set")) {
+            handleIssueSet(args);
+        } else {
+            help();
+        }
+    }
+
+    /**
+     * EFFECTS: Clear the certificates and return main.
+     * MODIFIES: this
+     */
+    @Override
+    public Screen exit() {
+        incomingCSR = null;
+        template = null;
+        return Screen.MAIN;
+    }
+
+    /**
+     * EFFECTS: Return "/subj/ %"
+     */
+    @Override
+    public String getPS1() {
+        return String.format("/%s/ %%", template.getSubject() == null
+                ? incomingCSR.getCertificationRequestInfo().getSubject()
+                : template.getSubject());
+    }
+}
diff --git a/src/main/ui/tui/JCA.java b/src/main/ui/tui/JCA.java
new file mode 100644
index 0000000..c23d610
--- /dev/null
+++ b/src/main/ui/tui/JCA.java
@@ -0,0 +1,220 @@
+package ui.tui;
+
+import model.asn1.exceptions.InvalidDBException;
+import model.asn1.exceptions.ParseException;
+import model.ca.CertificationAuthority;
+import persistence.Decoder;
+import persistence.FS;
+import ui.Utils;
+
+import java.io.IOException;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.Path;
+import java.security.NoSuchAlgorithmException;
+import java.security.spec.InvalidKeySpecException;
+import java.util.Scanner;
+
+/**
+ * Main program
+ */
+public class JCA {
+    /**
+     * Default db file (./data/ca.json)
+     */
+    private static final Path PATH_DEFAULT = Path.of("data", "ca.json");
+
+    /**
+     * Instances of the five screens;
+     */
+    private final UIHandler mainScreen;
+    private final UIHandler mgmtScreen;
+    private final UIHandler issueScreen;
+    private final UIHandler templatesScreen;
+    private final UIHandler templateSetScreen;
+    /**
+     * The CA
+     */
+    private CertificationAuthority ca;
+    /**
+     * The current screen.
+     */
+    private UIHandler screen;
+
+    /**
+     * There are unsaved changes.
+     */
+    private boolean unsaved = false;
+
+    /**
+     * EFFECTS: Init with main screen and empty CA. No private key and no CA cert.
+     * Throws {@link NoSuchAlgorithmException} when crypto issue happens.
+     */
+    public JCA() throws NoSuchAlgorithmException, InvalidKeySpecException {
+        this.mainScreen = new MainScreen(this);
+        this.mgmtScreen = new MgmtScreen(this);
+        this.issueScreen = new IssueScreen(this);
+        this.templatesScreen = new TemplatesScreen(this);
+        this.templateSetScreen = new TemplateSetScreen(this);
+
+        setScreen(Screen.MAIN);
+
+        this.ca = new CertificationAuthority();
+    }
+
+    /**
+     * EFFECT: Checks if the CA is installed or not (according to the desired state) and print if not matching. Returns
+     * true if matching.
+     */
+    public boolean checkCA(boolean requireInstalled) {
+        if (requireInstalled && ca.getCertificate() == null) {
+            System.out.println("No CA installed");
+            return false;
+        } else if (!requireInstalled && ca.getCertificate() != null) {
+            System.out.println("CA already installed");
+            return false;
+        }
+        return true;
+    }
+
+    /**
+     * EFFECTS: Read PEM from stdin, matched the given tag.
+     * Throws {@link ParseException} if the input is incorrect.
+     */
+    public Byte[] handleInputPEM(String desiredTag) throws ParseException {
+        final Scanner scanner = new Scanner(System.in);
+        StringBuilder in = new StringBuilder();
+        while (true) {
+            final String line = scanner.nextLine();
+            in.append(line);
+            in.append("\n");
+            if (line.matches("-----END .*-----")) {
+                break;
+            }
+        }
+        return Utils.parsePEM(Utils.byteToByte(in.toString().getBytes(StandardCharsets.UTF_8)), desiredTag);
+    }
+
+    /**
+     * EFFECT: Set the current screen with optional args. Exit the program when mode is null.
+     * MODIFIES: this
+     */
+    public void setScreen(Screen mode, Object... args) {
+        if (mode == null) {
+            System.exit(0);
+        }
+        switch (mode) {
+            case MAIN:
+                this.screen = mainScreen;
+                break;
+            case MGMT:
+                this.screen = mgmtScreen;
+                break;
+            case ISSUE:
+                this.screen = issueScreen;
+                break;
+            case TEMPLATES:
+                this.screen = templatesScreen;
+                break;
+            case TEMPLATE_SET:
+                this.screen = templateSetScreen;
+                break;
+        }
+        screen.enter(args);
+    }
+
+    /**
+     * EFFECTS: Read the database file and replace all local states.
+     * MODIFIES: this
+     */
+    private void load() {
+        if (unsaved) {
+            System.out.println("Current database is not saved yet.");
+            return;
+        }
+        try {
+            this.ca = Decoder.decodeCA(FS.read(PATH_DEFAULT));
+        } catch (InvalidDBException | NoSuchAlgorithmException e) {
+            System.out.println(e.getMessage());
+            if (e.getCause() != null) {
+                System.out.println(e.getCause().getMessage());
+                e.getCause().printStackTrace();
+            }
+        }
+    }
+
+    /**
+     * EFFECTS: Handle input line
+     * MODIFIES: this
+     */
+    private void handleLine(String... args) {
+        if (args[0].equals("log")) {
+            ca.getLogs().forEach(System.out::println);
+            return;
+        }
+        if ("help".equals(args[0])) {
+            screen.help();
+            System.out.println("log\tView audit logs");
+            System.out.println("load\tLoad database");
+            System.out.println("save\tSave database");
+        } else if ("commit".equals(args[0])) {
+            screen.commit();
+        } else if ("show".equals(args[0])) {
+            screen.show();
+        } else if ("exit".equals(args[0])) {
+            setScreen(screen.exit());
+        } else if ("save".equals(args[0])) {
+            save();
+        } else if ("load".equals(args[0])) {
+            load();
+        } else {
+            screen.command(args);
+        }
+        printPS1();
+    }
+
+    /**
+     * EFFECTS: Print the '*user@JCA PS1' line
+     */
+    private void printPS1() {
+        System.out.printf("%s%s@JCA %s ",
+                unsaved ? "*" : "",
+                ca.getUser(),
+                screen.getPS1());
+    }
+
+    /**
+     * EFFECTS: Save the DB
+     */
+    public void save() {
+        try {
+            FS.write(PATH_DEFAULT, Decoder.encodeCA(ca));
+            unsaved = false;
+        } catch (IOException e) {
+            System.out.println(e.getMessage());
+        }
+    }
+
+    /**
+     * EFFECTS: Run the program
+     */
+    public void run() {
+        printPS1();
+        final Scanner scanner = new Scanner(System.in);
+        while (true) {
+            String[] args = scanner.nextLine().split(" ");
+            if (args.length <= 0 || args[0].isBlank()) {
+                printPS1();
+                continue;
+            }
+            handleLine(args);
+        }
+    }
+
+    public void setUnsaved(boolean unsaved) {
+        this.unsaved = unsaved;
+    }
+
+    public CertificationAuthority getCa() {
+        return ca;
+    }
+}
diff --git a/src/main/ui/tui/MainScreen.java b/src/main/ui/tui/MainScreen.java
new file mode 100644
index 0000000..860eff7
--- /dev/null
+++ b/src/main/ui/tui/MainScreen.java
@@ -0,0 +1,234 @@
+package ui.tui;
+
+import model.asn1.ASN1Object;
+import model.asn1.UtcTime;
+import model.asn1.exceptions.ParseException;
+import model.asn1.parsing.BytesReader;
+import model.ca.Template;
+import model.csr.CertificationRequest;
+import model.pki.cert.Certificate;
+import model.pki.crl.CertificateList;
+import model.pki.crl.Reason;
+import model.pki.crl.RevokedCertificate;
+import ui.Utils;
+
+import java.io.File;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.io.OutputStream;
+import java.time.ZoneId;
+import java.time.ZonedDateTime;
+import java.util.Optional;
+
+/**
+ * The main screen that handles submenus (mgmt / issue / template), list certs, revoke certs, generate CRLs.
+ */
+public class MainScreen implements UIHandler {
+    private final JCA session;
+
+    /**
+     * EFFECTS: Init with the parent session.
+     */
+    public MainScreen(JCA session) {
+        this.session = session;
+    }
+
+    /**
+     * EFFECTS: Print help
+     */
+    @Override
+    public void help() {
+        System.out.print("mgmt\tView and manage the CA certificate\n"
+                + "issue\tIssue a certificate\n"
+                + "show\tList all issued certificates\n"
+                + "export\tExport a certificate to file (DER)\n"
+                + "template\tManage templates\n"
+                + "revoke\tRevoke a certificate\n"
+                + "crl\t\tSign CRL\n"
+                + "log\t\tView audit logs\n"
+                + "exit\tExit\n"
+                + "help\tPrint this message\n");
+    }
+
+    /**
+     * EFFECTS: Print each issued cert in Subject Serial Status format.
+     */
+    @Override
+    public void show() {
+        session.getCa().getSigned().forEach(cert -> {
+            System.out.printf("%s\t%d\t%s\n",
+                    cert.getCertificate().getSubject().toString(),
+                    cert.getCertificate().getSerialNumber().getLong(),
+                    session.getCa().getRevoked().stream().anyMatch(rev -> rev.getSerialNumber().getLong()
+                            == cert.getCertificate().getSerialNumber().getLong()) ? "REVOKED" : "OK");
+        });
+    }
+
+    /**
+     * EFFECTS: Read the input CSR.
+     */
+    private CertificationRequest handleIssueInputCSR() {
+        try {
+            return new CertificationRequest(new BytesReader(session.handleInputPEM("CERTIFICATE REQUEST")),
+                    false);
+        } catch (ParseException e) {
+            System.out.println(e.getMessage());
+            return null;
+        }
+    }
+
+    /**
+     * EFFECTS: Handle the issue command. Read CSR, find template, switch to issue screen.
+     */
+    private void handleIssue(String... args) {
+        if (!session.checkCA(true)) {
+            return;
+        }
+        if (args.length <= 1) {
+            System.out.println("Usage: issue <template>");
+            return;
+        }
+        Template tmp = session.getCa().findTemplate(args[1], true);
+        if (tmp == null) {
+            System.out.println("Cannot find the template specified");
+            return;
+        }
+        CertificationRequest req = handleIssueInputCSR();
+        if (req != null) {
+            session.setScreen(Screen.ISSUE, req, new Template(tmp.getName(),
+                    true,
+                    tmp.getSubject(),
+                    tmp.getValidity()));
+        }
+    }
+
+    /**
+     * EFFECTS: Find issued and not revoked certificate by serial. Return null if not found.
+     */
+    private Certificate findCertBySerial(int serial) {
+        Optional<Certificate> c = session.getCa().getSigned()
+                .stream()
+                .filter(cert -> cert.getCertificate().getSerialNumber().getLong() == serial)
+                .findFirst();
+        if (c.isEmpty()) {
+            System.out.println("Cannot find the certificate specified");
+            return null;
+        }
+        if (session.getCa().getRevoked().stream().anyMatch(rev -> rev.getSerialNumber().getLong() == serial)) {
+            System.out.println("The certificate has already been revoked.");
+            return null;
+        }
+        return c.get();
+    }
+
+    /**
+     * EFFECTS: Handle the revoke command and log it.
+     * MODIFIES: session
+     */
+    private void handleRevoke(String... args) {
+        if (args.length < 3) {
+            System.out.println("Usage: revoke <serial> <reason>");
+            return;
+        }
+        try {
+            final Reason reason = Reason.valueOf(args[2]);
+            int serial = Integer.parseInt(args[1]);
+            Certificate c = findCertBySerial(serial);
+            if (c == null) {
+                return;
+            }
+            session.getCa().revoke(new RevokedCertificate(ASN1Object.TAG_SEQUENCE, null,
+                    c.getCertificate().getSerialNumber(),
+                    new UtcTime(UtcTime.TAG, null, ZonedDateTime.now(ZoneId.of("UTC"))), reason));
+            session.save();
+        } catch (IllegalArgumentException ignored) {
+            System.out.println("Illegal serial number or reason");
+        }
+    }
+
+    /**
+     * EFFECTS: Export a cert to file
+     */
+    private void handleExport(String... args) {
+        if (args.length < 3) {
+            System.out.println("Usage: export <serial> <path>");
+            return;
+        }
+        try {
+            int serial = Integer.parseInt(args[1]);
+            Certificate c = findCertBySerial(serial);
+            if (c == null) {
+                return;
+            }
+            final File fd = new File(args[2]);
+            final OutputStream out = new FileOutputStream(fd);
+            out.write(Utils.byteToByte(c.encodeDER()));
+            out.close();
+        } catch (IllegalArgumentException ignored) {
+            System.out.println("Illegal serial number");
+        } catch (IOException e) {
+            System.out.println(e.getMessage());
+        }
+    }
+
+    /**
+     * EFFECTS: Issue a CRL and do audit log.
+     * MODIFIES: session
+     */
+    private void handleCRL() {
+        if (!session.checkCA(true)) {
+            return;
+        }
+        try {
+            CertificateList crl = session.getCa().signCRL();
+            session.save();
+            System.out.println(Utils.toPEM(crl.encodeDER(), "X509 CRL"));
+        } catch (Throwable e) {
+            System.out.println(e.getMessage());
+        }
+    }
+
+    /**
+     * EFFECTS: Handle commands
+     */
+    @Override
+    public void command(String... args) {
+        switch (args[0]) {
+            case "mgmt":
+                session.setScreen(Screen.MGMT);
+                return;
+            case "issue":
+                handleIssue(args);
+                return;
+            case "revoke":
+                handleRevoke(args);
+                return;
+            case "export":
+                handleExport(args);
+                return;
+            case "template":
+                session.setScreen(Screen.TEMPLATES);
+                return;
+            case "crl":
+                handleCRL();
+                return;
+        }
+        help();
+    }
+
+    /**
+     * EFFECTS: Exit the program
+     */
+    @Override
+    public Screen exit() {
+        return null;
+    }
+
+    /**
+     * EFFECTS: return "/ %"
+     */
+    @Override
+    public String getPS1() {
+        return "/ %";
+    }
+}
diff --git a/src/main/ui/tui/MgmtScreen.java b/src/main/ui/tui/MgmtScreen.java
new file mode 100644
index 0000000..007bd0e
--- /dev/null
+++ b/src/main/ui/tui/MgmtScreen.java
@@ -0,0 +1,153 @@
+package ui.tui;
+
+import model.asn1.exceptions.InvalidCAException;
+import model.asn1.exceptions.ParseException;
+import model.asn1.parsing.BytesReader;
+import model.csr.CertificationRequest;
+import model.pki.cert.Certificate;
+import model.pki.cert.TbsCertificate;
+import ui.Utils;
+
+import java.security.NoSuchAlgorithmException;
+import java.util.Base64;
+
+/**
+ * Manage the private key and CA certificate. It can print the public key, generate CSR, and install CA cert.
+ */
+public class MgmtScreen implements UIHandler {
+    private final JCA session;
+
+    /**
+     * EFFECTS: Init with the parent session.
+     */
+    public MgmtScreen(JCA session) {
+        this.session = session;
+    }
+
+    /**
+     * EFFECTS: Print help
+     */
+    @Override
+    public void help() {
+        System.out.print("show\tView the public key and CA certificate\n"
+                + "genkey\tGenerate a RSA private key\n"
+                + "csr\tGenerate a CSR for a upper-level CA to sign\n"
+                + "install\tInstall a CA certificate\n"
+                + "exit\tGo to main menu\n"
+                + "help\tPrint this message\n");
+    }
+
+    /**
+     * EFFECTS: Format the public key and CA
+     */
+    @Override
+    public void show() {
+        if (session.getCa().getPublicKey() == null) {
+            System.out.println("No private key installed");
+        } else {
+            System.out.println("Public Key (RSA2048):");
+            System.out.printf("\tModules:\t\t%s\n", session.getCa().getPublicKey().getModulus().toString(10));
+            System.out.printf("\tPublic Exponent:\t%s\n",
+                    session.getCa().getPublicKey().getPublicExponent().toString(16));
+        }
+        if (!session.checkCA(true)) {
+            return;
+        }
+        final TbsCertificate info = session.getCa().getCertificate().getCertificate();
+        System.out.printf("Subject:\t%s\n", info.getSubject().toString());
+        System.out.printf("Issuer:\t%s\n", info.getIssuer().toString());
+        System.out.printf("Not Before:\t%s\n", info.getValidity().getNotBefore().getTimestamp());
+        System.out.printf("Not After:\t%s\n", info.getValidity().getNotAfter().getTimestamp());
+        System.out.printf("Signature:\t%s\n",
+                Base64.getEncoder().encodeToString(Utils.byteToByte(info.getSubjectPublicKeyInfo()
+                        .getSubjectPublicKey().getConvertedVal())));
+    }
+
+    /**
+     * EFFECT: Generate a CSR
+     * MODIFIES: session
+     */
+    private void handleCSR() {
+        if (!session.checkCA(false)) {
+            return;
+        }
+        try {
+            CertificationRequest req = session.getCa().signCSR();
+            System.out.println(Utils.toPEM(req.encodeDER(), "CERTIFICATE REQUEST"));
+            session.setUnsaved(true);
+        } catch (Throwable e) {
+            System.out.println(e.getMessage());
+        }
+    }
+
+    /**
+     * EFFECTS: Handle the 'install' command. Read incoming certificate and validate it.
+     * MODIFIES: session
+     */
+    private void handleInstall() {
+        if (!session.checkCA(false)) {
+            return;
+        }
+        try {
+            final Byte[] in = session.handleInputPEM("CERTIFICATE");
+            final Certificate cert = new Certificate(new BytesReader(in), false);
+            session.getCa().installCertificate(cert);
+            session.setUnsaved(true);
+        } catch (InvalidCAException | ParseException e) {
+            System.out.println(e.getMessage());
+        }
+    }
+
+    /**
+     * EFFECTS: Handle the 'genkey' command. Generate a RSA2048 private key.
+     * MODIFIES: session
+     */
+    private void handleGenKey() {
+        if (session.getCa().getPublicKey() != null) {
+            System.out.println("A private key is already installed.");
+        }
+        try {
+            session.getCa().generateKey();
+            session.setUnsaved(true);
+        } catch (NoSuchAlgorithmException e) {
+            System.out.println(e.getMessage());
+        }
+    }
+
+    /**
+     * EFFECTS: Handle commands.
+     */
+    @Override
+    public void command(String... args) {
+        switch (args[0]) {
+            case "genkey":
+                handleGenKey();
+                break;
+            case "csr":
+                handleCSR();
+                break;
+            case "install":
+                handleInstall();
+                break;
+            default:
+                help();
+                break;
+        }
+    }
+
+    /**
+     * EFFECTS: Go to main menu
+     */
+    @Override
+    public Screen exit() {
+        return Screen.MAIN;
+    }
+
+    /**
+     * EFFECTS: return "/ca/ #"
+     */
+    @Override
+    public String getPS1() {
+        return "/ca/ #";
+    }
+}
\ No newline at end of file
diff --git a/src/main/ui/tui/Screen.java b/src/main/ui/tui/Screen.java
new file mode 100644
index 0000000..413fe8a
--- /dev/null
+++ b/src/main/ui/tui/Screen.java
@@ -0,0 +1,31 @@
+package ui.tui;
+
+/**
+ * The screen type
+ */
+public enum Screen {
+    /**
+     * Main menu (mgmt, issue, template, crl, show, revoke, log)
+     */
+    MAIN,
+
+    /**
+     * The CA management menu (show, csr, install)
+     */
+    MGMT,
+
+    /**
+     * The issue menu (show, set, commit)
+     */
+    ISSUE,
+
+    /**
+     * The templates menu (show, add, enable, disable, remove)
+     */
+    TEMPLATES,
+
+    /**
+     * The template edit menu (show, set, commit)
+     */
+    TEMPLATE_SET
+}
diff --git a/src/main/ui/tui/TemplateSetScreen.java b/src/main/ui/tui/TemplateSetScreen.java
new file mode 100644
index 0000000..0f6df3a
--- /dev/null
+++ b/src/main/ui/tui/TemplateSetScreen.java
@@ -0,0 +1,157 @@
+package ui.tui;
+
+import model.asn1.exceptions.ParseException;
+import model.ca.Template;
+import model.x501.Name;
+
+/**
+ * The screen that modifies the properties of a single template and add it to the store.
+ */
+public class TemplateSetScreen implements UIHandler {
+    private final JCA session;
+
+    /**
+     * EFFECTS: Init with session.
+     */
+    public TemplateSetScreen(JCA session) {
+        this.session = session;
+    }
+
+    private Template template;
+
+    /**
+     * EFFECTS: Print help
+     */
+    @Override
+    public void help() {
+        System.out.println("show\tView the current template settings\n"
+                + "set\tSet key value\n"
+                + "commit\tSave the template\n"
+                + "exit\tDiscard changes\n"
+                + "help\tPrint this help message\n");
+    }
+
+    /**
+     * EFFECTS: Parse and set / unset the subject of the template
+     * MODIFIES: this
+     */
+    private void handleSetSubject(String val) {
+        try {
+            if (val == null) {
+                template = new Template(template.getName(), template.isEnabled(), (Name) null, template.getValidity());
+            } else {
+                template = new Template(template.getName(), template.isEnabled(), val, template.getValidity());
+            }
+        } catch (ParseException e) {
+            System.out.println(e.getMessage());
+        }
+    }
+
+    /**
+     * EFFECTS: Set the validity of the template to the given integer
+     * MODIFIES: this
+     */
+    private void handleSetValidity(String val) {
+        if (val == null) {
+            System.out.println("Cannot unset validity");
+            return;
+        }
+        try {
+            long i = Long.parseLong(val);
+            if (i <= 0) {
+                System.out.println("Invalid validity days");
+                return;
+            }
+            template = new Template(template.getName(), template.isEnabled(), template.getSubject(), i);
+        } catch (NumberFormatException ignored) {
+            System.out.println("Invalid validity days");
+        }
+    }
+
+    /**
+     * EFFECTS: Handle the `set` command.
+     * MODIFIES: this
+     */
+    private void handleSet(String... args) {
+        if (args.length != 2 && args.length != 3) {
+            System.out.println("Usage: set <key> <value>");
+            System.out.println("Supported keys: subject validity");
+            return;
+        }
+        String val = args.length == 3 ? args[2] : null;
+        switch (args[1]) {
+            case "subject":
+                handleSetSubject(val);
+                break;
+            case "validity":
+                handleSetValidity(val);
+                break;
+            default:
+                System.out.println("Unknown key");
+                break;
+        }
+    }
+
+    /**
+     * EFFECTS: Add the template to store and switch to templates screen.
+     * MODIFIES: session
+     */
+    @Override
+    public void commit() {
+        session.getCa().addTemplate(template);
+        session.setUnsaved(true);
+        session.setScreen(Screen.TEMPLATES);
+    }
+
+    /**
+     * EFFECTS: Show template info.
+     */
+    @Override
+    public void show() {
+        System.out.println("Subject:\t" + template.getSubject());
+        System.out.println("Validity:\t" + template.getValidity() + " days");
+    }
+
+    /**
+     * EFFECTS: Handle commands
+     */
+    @Override
+    public void command(String... args) {
+        switch (args[0]) {
+            case "set":
+                handleSet(args);
+                break;
+            default:
+            case "help":
+                help();
+                break;
+        }
+    }
+
+    /**
+     * EFFECTS: Return to templates list and clear the current template in editing.
+     */
+    @Override
+    public Screen exit() {
+        template = null;
+        return Screen.TEMPLATES;
+    }
+
+    /**
+     * EFFECTS: yuuta@JCA /templates/name/ %
+     */
+    @Override
+    public String getPS1() {
+        return String.format("/templates/%s/ %%", template.getName());
+    }
+
+    /**
+     * EFFECT: Edit args[0].
+     * REQUIRES: args.length = 1; args[0] instanceof Template
+     * MODIFIES: args[0]
+     */
+    @Override
+    public void enter(Object... args) {
+        template = (Template) args[0];
+    }
+}
\ No newline at end of file
diff --git a/src/main/ui/tui/TemplatesScreen.java b/src/main/ui/tui/TemplatesScreen.java
new file mode 100644
index 0000000..6b7f18c
--- /dev/null
+++ b/src/main/ui/tui/TemplatesScreen.java
@@ -0,0 +1,138 @@
+package ui.tui;
+
+import model.ca.Template;
+import model.x501.Name;
+
+/**
+ * The screen that allows users to list templates and manage them.
+ */
+public class TemplatesScreen implements UIHandler {
+    private final JCA session;
+
+    /**
+     * EFFECTS: Init with the session.
+     */
+    public TemplatesScreen(JCA session) {
+        this.session = session;
+    }
+
+    /**
+     * EFFECTS: Print help.
+     */
+    @Override
+    public void help() {
+        System.out.println("show\tList templates\n"
+                + "add\tCreate a new template\n"
+                + "enable\tEnable a template\n"
+                + "disable\tDisable a template\n"
+                + "delete\tDelete a template\n"
+                + "exit\tGo to main menu\n"
+                + "help\tPrint this message");
+    }
+
+    /**
+     * EFFECTS: List templates in Name[ENABLED / DISABLED] Subject Validity format.
+     */
+    @Override
+    public void show() {
+        session.getCa().getTemplates().forEach(tem ->
+                System.out.printf("%s[%s]\t%s\t%d Days\n",
+                        tem.getName(),
+                        tem.isEnabled() ? "ENABLED" : "DISABLED",
+                        tem.getSubject(),
+                        tem.getValidity()));
+    }
+
+    /**
+     * EFFECTS: Create a new template with the given name and switch to the template set screen.
+     */
+    private void handleAdd(String... args) {
+        if (args.length <= 1) {
+            System.out.println("Usage: add <name>");
+            return;
+        }
+        if (session.getCa().findTemplate(args[1], false) != null) {
+            System.out.println("The template already exists.");
+            return;
+        }
+
+        session.setScreen(Screen.TEMPLATE_SET,
+                new Template(args[1], false, (Name) null, 30));
+    }
+
+    /**
+     * EFFECTS: Handle the enable / disable commands.
+     * MODIFIES: session
+     */
+    private void handleEnableDisable(boolean enable, String... args) {
+        if (args.length <= 1) {
+            System.out.printf("Usage: %s <template>\n", enable ? "enable" : "disable");
+            return;
+        }
+        Template tmp = session.getCa().findTemplate(args[1], false);
+        if (tmp == null) {
+            System.out.println("Cannot find the template specified");
+            return;
+        }
+        session.getCa().setTemplateEnable(tmp, enable);
+        session.setUnsaved(true);
+    }
+
+    /**
+     * EFFECTS: Handle the delete command
+     * MODIFIES: session
+     */
+    private void handleDelete(String... args) {
+        if (args.length <= 1) {
+            System.out.println("Usage: delete <template>");
+            return;
+        }
+        Template tmp = session.getCa().findTemplate(args[1], true);
+        if (tmp == null) {
+            System.out.println("Cannot find the template specified");
+            return;
+        }
+        session.getCa().removeTemplate(tmp);
+        session.setUnsaved(true);
+    }
+
+    /**
+     * EFFECTS: Handle commands.
+     */
+    @Override
+    public void command(String... args) {
+        switch (args[0]) {
+            case "add":
+                handleAdd(args);
+                break;
+            case "enable":
+                handleEnableDisable(true, args);
+                break;
+            case "disable":
+                handleEnableDisable(false, args);
+                break;
+            case "delete":
+                handleDelete(args);
+                break;
+            default:
+                help();
+                break;
+        }
+    }
+
+    /**
+     * EFFECTS: Go to main menu.
+     */
+    @Override
+    public Screen exit() {
+        return Screen.MAIN;
+    }
+
+    /**
+     * EFFECTS: Return "/templates/ %"
+     */
+    @Override
+    public String getPS1() {
+        return "/templates/ %";
+    }
+}
diff --git a/src/main/ui/tui/UIHandler.java b/src/main/ui/tui/UIHandler.java
new file mode 100644
index 0000000..672fd50
--- /dev/null
+++ b/src/main/ui/tui/UIHandler.java
@@ -0,0 +1,45 @@
+package ui.tui;
+
+/**
+ * Represents a screen
+ */
+public interface UIHandler {
+    /**
+     * EFFECTS: Called when the screen is switched to.
+     */
+    default void enter(Object... args) {
+
+    }
+
+    /**
+     * EFFECTS: Show objects. command() will not be called.
+     */
+    void show();
+
+    /**
+     * EFFECTS: Commit changes and exit. command() will not be called.
+     */
+    default void commit() {
+    }
+
+    /**
+     * EFFECTS: Discard changes and exit. command() will not be called. Returns the next screen.
+     */
+    Screen exit();
+
+    /**
+     * EFFECTS: Run help. command() will not be called.
+     */
+    void help();
+
+    /**
+     * EFFECTS: Any commands rather than commit / exit / help.
+     * REQUIRES: args != null && args.length >= 1
+     */
+    void command(String... args);
+
+    /**
+     * EFFECTS: Return the current PS1 prompt.
+     */
+    String getPS1();
+}
diff --git a/src/main/ui/widgets/CertEditDialog.java b/src/main/ui/widgets/CertEditDialog.java
deleted file mode 100644
index bad5a4f..0000000
--- a/src/main/ui/widgets/CertEditDialog.java
+++ /dev/null
@@ -1,108 +0,0 @@
-package ui.widgets;
-
-import javax.swing.*;
-import java.awt.*;
-import java.awt.event.ActionEvent;
-import java.awt.event.KeyEvent;
-import java.awt.event.WindowAdapter;
-import java.awt.event.WindowEvent;
-
-import static java.awt.GridBagConstraints.HORIZONTAL;
-import static java.awt.GridBagConstraints.WEST;
-import static ui.widgets.UIUtils.btn;
-
-/**
- * A common dialog for cert / template editing. It will close upon Esc or Cancel.
- * +---------------------------++---------------------------++---------------------------+
- * |  Dialog                 X ||  New Template           X ||  Issue new certificate  X |
- * |                           ||                           ||                           |
- * |Template:          (TBD)   ||Template:         _________||Template:       (Drop down)|
- * |Subject:          _________||Subject:          _________||Subject:         _________ |
- * |Validity (Days):  (Spinner)||Validity (Days):  (Spinner)||Validity (Days):  (Spinner)|
- * |                           ||                           ||                           |
- * |              Button Cancel||                 Add Cancel||               Issue Cancel|
- * +---------------------------++---------------------------++---------------------------+
- */
-public abstract class CertEditDialog<T> extends JDialog {
-    /**
-     * The result.
-     */
-    protected T res;
-
-    /**
-     * Root pane.
-     */
-    protected JPanel contentPane = new JPanel();
-    protected JButton buttonOK = btn("", this::onOK);
-    protected JTextField textFieldSubject = new JTextField();
-    protected JSpinner spinnerValidity =
-            new JSpinner(new SpinnerNumberModel(60, 1, null, 0));
-
-    /**
-     * EFFECTS: Render the dialog, leaving title and OK button text blank.
-     */
-    public CertEditDialog() {
-        contentPane.setLayout(new BoxLayout(contentPane, BoxLayout.PAGE_AXIS));
-        contentPane.setBorder(BorderFactory.createEmptyBorder(8, 8, 8, 8));
-        contentPane.add(renderForm());
-
-        contentPane.add(UIUtils.createActionsPane(buttonOK, btn("Cancel", this::onCancel)));
-
-        setContentPane(contentPane);
-        setModal(true);
-        getRootPane().setDefaultButton(buttonOK);
-        setDefaultCloseOperation(DO_NOTHING_ON_CLOSE);
-
-        addWindowListener(new WindowAdapter() {
-            public void windowClosing(WindowEvent e) {
-                onCancel(null);
-            }
-        });
-
-        contentPane.registerKeyboardAction(this::onCancel,
-                KeyStroke.getKeyStroke(KeyEvent.VK_ESCAPE, 0),
-                JComponent.WHEN_ANCESTOR_OF_FOCUSED_COMPONENT);
-    }
-
-    /**
-     * EFFECTS: Render the form.
-     */
-    private JPanel renderForm() {
-        final JPanel panelForm = new JPanel(new GridBagLayout());
-        panelForm.add(new JLabel("Template: "), new GCBuilder().anchor(WEST).build());
-        panelForm.add(new JLabel("Subject: "), new GCBuilder().gridY(1).anchor(WEST).build());
-        panelForm.add(new JLabel("Validity (Days): "), new GCBuilder().gridY(2).anchor(WEST).build());
-        panelForm.add(createTemplateComponent(), new GCBuilder().gridXY(1, 0).anchor(WEST)
-                .fill(HORIZONTAL).build());
-        panelForm.add(textFieldSubject, new GCBuilder().gridXY(1, 1).anchor(WEST).fill(HORIZONTAL).build());
-        panelForm.add(spinnerValidity, new GCBuilder().gridXY(1, 2).anchor(WEST).fill(HORIZONTAL).build());
-        panelForm.add(new JPanel(), new GCBuilder().gridXY(1, 3).expandXY().fill(HORIZONTAL).build());
-        return panelForm;
-    }
-
-    /**
-     * EFFECTS: Create the component for subject.
-     */
-    protected abstract JComponent createTemplateComponent();
-
-    /**
-     * EFFECTS: Handle OK.
-     */
-    protected abstract void onOK(ActionEvent ev);
-
-    /**
-     * EFFECTS: Handle cancel: clear result and close dialog.
-     * MODIFIES: this
-     */
-    private void onCancel(ActionEvent ev) {
-        res = null;
-        dispose();
-    }
-
-    /**
-     * EFFECTS: Get the result.
-     */
-    public T getRes() {
-        return res;
-    }
-}
diff --git a/src/main/ui/widgets/CertTableModel.java b/src/main/ui/widgets/CertTableModel.java
deleted file mode 100644
index 0259e1b..0000000
--- a/src/main/ui/widgets/CertTableModel.java
+++ /dev/null
@@ -1,129 +0,0 @@
-package ui.widgets;
-
-import model.ca.CertificationAuthority;
-import model.pki.cert.Certificate;
-import model.pki.crl.RevokedCertificate;
-
-import javax.swing.*;
-import javax.swing.table.AbstractTableModel;
-import java.time.format.DateTimeFormatter;
-import java.util.List;
-
-/**
- * Table model that displays issued certificates.
- */
-public class CertTableModel extends AbstractTableModel {
-    /**
-     * Valid certificate icon.
-     */
-    private static final ImageIcon ICON_OK =
-            new ImageIcon(CertTableModel.class.getResource("/verified.png"));
-
-    /**
-     * Revoked certificate icon (same as toolbar revoke icon).
-     */
-    private static final ImageIcon ICON_REVOKED =
-            new ImageIcon(CertTableModel.class.getResource("/deletetest.png"));
-
-    /**
-     * Columns
-     */
-    private static final String[] COLS = new String[] {
-            "", // Icon
-            "Serial",
-            "Subject",
-            "Signed",
-            "Expires"
-    };
-
-    /**
-     * Pointer to {@link CertificationAuthority#getSigned()}
-     */
-    private List<Certificate> ptrData;
-
-    /**
-     * Pointer to {@link CertificationAuthority#getRevoked()}
-     */
-    private List<RevokedCertificate> ptrRevokedData;
-
-    /**
-     * EFFECTS: Set pointer to certs
-     * MODIFIES: this
-     */
-    public void setPtrData(List<Certificate> ptrData) {
-        this.ptrData = ptrData;
-    }
-
-    /**
-     * EFFECTS: Set pointer to revoked
-     * MODIFIES: this
-     */
-    public void setPtrRevokedData(List<RevokedCertificate> ptrRevokedData) {
-        this.ptrRevokedData = ptrRevokedData;
-    }
-
-    /**
-     * EFFECTS: Count rows.
-     */
-    @Override
-    public int getRowCount() {
-        return ptrData == null ? 0 : ptrData.size();
-    }
-
-    /**
-     * EFFECTS: Count columns.
-     */
-    @Override
-    public int getColumnCount() {
-        return COLS.length;
-    }
-
-    /**
-     * EFFECTS: Get column name.
-     * REQUIRES: column in [9, getColumnCount())
-     */
-    @Override
-    public String getColumnName(int column) {
-        return COLS[column];
-    }
-
-    /**
-     * EFFECTS: Return the value for a cell:
-     *          ImageIcon (Valid / Revoked)
-     *          String (Serial number)
-     *          String (Subject)
-     *          String (NotBefore)
-     *          String (NotAfter)
-     *          Throws {@link IllegalArgumentException} if columnIndex is not in 0 ~ 4
-     * REQUIRES: rowIndex must in range.
-     */
-    @Override
-    public Object getValueAt(int rowIndex, int columnIndex) {
-        final Certificate e = ptrData.get(rowIndex);
-        switch (columnIndex) {
-            case 0: return ptrRevokedData.stream().anyMatch(r ->
-                    r.getSerialNumber().getLong() == e.getCertificate().getSerialNumber().getLong()
-            ) ? ICON_REVOKED : ICON_OK;
-            case 1: return e.getCertificate().getSerialNumber().getLong();
-            case 2: return e.getCertificate().getSubject().toString();
-            case 3:
-                return e.getCertificate().getValidity().getNotBefore().getTimestamp()
-                        .format(DateTimeFormatter.ISO_LOCAL_DATE_TIME);
-            case 4:
-                return e.getCertificate().getValidity().getNotAfter().getTimestamp()
-                        .format(DateTimeFormatter.ISO_LOCAL_DATE_TIME);
-            default: throw new IllegalArgumentException();
-        }
-    }
-
-    /**
-     * EFFECTS: Return ImageIcon for 0, String otherwise.
-     */
-    @Override
-    public Class<?> getColumnClass(int columnIndex) {
-        switch (columnIndex) {
-            case 0: return ImageIcon.class;
-            default: return String.class;
-        }
-    }
-}
diff --git a/src/main/ui/widgets/GCBuilder.java b/src/main/ui/widgets/GCBuilder.java
deleted file mode 100644
index 0590cc1..0000000
--- a/src/main/ui/widgets/GCBuilder.java
+++ /dev/null
@@ -1,213 +0,0 @@
-package ui.widgets;
-
-import java.awt.*;
-
-/**
- * A builder for {@link GridBagConstraints}.
- */
-public class GCBuilder {
-    /**
-     * Grix X and Y, defaults to {@link GridBagConstraints#RELATIVE}
-     */
-    private int gridX = GridBagConstraints.RELATIVE;
-
-    private int gridY = GridBagConstraints.RELATIVE;
-
-    /**
-     * Weight X and Y, [0.0, 1.0], defaults to 0.0
-     */
-    private double weightX = 0.0;
-
-    private double weightY = 0.0;
-
-    /**
-     * Anchor, defaults to {@link GridBagConstraints#CENTER}
-     */
-    private int anchor = GridBagConstraints.CENTER;
-
-    /**
-     * How to stretch the component, defaults to {@link GridBagConstraints#NONE}
-     */
-    private int fill = GridBagConstraints.NONE;
-
-    /**
-     * Insects in pixels.
-     */
-    private int insectTop = 0;
-
-    private int insectLeft = 0;
-
-    private int insectRight = 0;
-
-    private int insectBottom = 0;
-
-    /**
-     * EFFECTS: Build the {@link GridBagConstraints} based on parameters.
-     * Grid width, grid height, ipad X, ipad Y will be 1, 1, 0, 0.
-     */
-    public GridBagConstraints build() {
-        return new GridBagConstraints(gridX, gridY,
-                1, 1,
-                weightX, weightY,
-                anchor, fill,
-                new Insets(insectTop, insectLeft, insectBottom, insectRight),
-                0, 0);
-    }
-
-    /**
-     * EFFECTS: Set grid X and Y.
-     * REQUIRES: > 0
-     * MODIFIES: this
-     */
-    public GCBuilder gridXY(int gridX, int gridY) {
-        return this.gridX(gridX).gridY(gridY);
-    }
-
-    /**
-     * EFFECTS: Set grid X.
-     * REQUIRES: > 0
-     * MODIFIES: this
-     */
-    public GCBuilder gridX(int gridX) {
-        this.gridX = gridX;
-        return this;
-    }
-
-    /**
-     * EFFECTS: Set grid Y.
-     * REQUIRES: > 0
-     * MODIFIES: this
-     */
-    public GCBuilder gridY(int gridY) {
-        this.gridY = gridY;
-        return this;
-    }
-
-    /**
-     * EFFECTS: Set weight X and Y.
-     * REQUIRES: [0.0, 1.0]
-     * MODIFIES: this
-     */
-    public GCBuilder weightXY(double weightX, double weightY) {
-        return this.weightX(weightX).weightY(weightY);
-    }
-
-    /**
-     * EFFECTS: Set weight X and Y to 1.0
-     * MODIFIES: this
-     */
-    public GCBuilder expandXY() {
-        return this.expandX().expandY();
-    }
-
-    /**
-     * EFFECTS: Set weight X to 1.0
-     * MODIFIES: this
-     */
-    public GCBuilder expandX() {
-        return this.weightX(1.0);
-    }
-
-    /**
-     * EFFECTS: Set weight X to 1.0
-     * MODIFIES: this
-     */
-    public GCBuilder weightX(double weightX) {
-        this.weightX = weightX;
-        return this;
-    }
-
-    /**
-     * EFFECTS: Set weight Y to 1.0
-     * MODIFIES: this
-     */
-    public GCBuilder expandY() {
-        return this.weightY(1.0);
-    }
-
-    /**
-     * EFFECTS: Set weight X to 1.0
-     * MODIFIES: this
-     */
-    public GCBuilder weightY(double weightY) {
-        this.weightY = weightY;
-        return this;
-    }
-
-    /**
-     * EFFECTS: Set anchor.
-     * REQUIRES: anchor in {@link GridBagConstraints} constants.
-     * MODIFIES: this
-     */
-    public GCBuilder anchor(int anchor) {
-        this.anchor = anchor;
-        return this;
-    }
-
-    /**
-     * EFFECTS: Set fill.
-     * REQUIRES: fill in {@link GridBagConstraints} constants.
-     * MODIFIES: this
-     */
-    public GCBuilder fill(int fill) {
-        this.fill = fill;
-        return this;
-    }
-
-    /**
-     * EFFECTS: Set insects to be 8, 8, 8, 8
-     * MODIFIES: this
-     */
-    public GCBuilder marginInsects() {
-        return this.insects(8, 8, 8, 8);
-    }
-
-    /**
-     * EFFECTS: Set insects.
-     * REQUIRES: >= 0
-     * MODIFIES: this
-     */
-    public GCBuilder insects(int top, int left, int bottom, int right) {
-        return this.insectTop(top).insectLeft(left).insectBottom(bottom).insectRight(right);
-    }
-
-    /**
-     * EFFECTS: Set top insect
-     * REQUIRES: >= 0
-     * MODIFIES: this
-     */
-    public GCBuilder insectTop(int insectTop) {
-        this.insectTop = insectTop;
-        return this;
-    }
-
-    /**
-     * EFFECTS: Set left insect
-     * REQUIRES: >= 0
-     * MODIFIES: this
-     */
-    public GCBuilder insectLeft(int insectLeft) {
-        this.insectLeft = insectLeft;
-        return this;
-    }
-
-    /**
-     * EFFECTS: Set right insect
-     * REQUIRES: >= 0
-     * MODIFIES: this
-     */
-    public GCBuilder insectRight(int insectRight) {
-        this.insectRight = insectRight;
-        return this;
-    }
-
-    /**
-     * EFFECTS: Set bottom insect
-     * REQUIRES: >= 0
-     * MODIFIES: this
-     */
-    public GCBuilder insectBottom(int insectBottom) {
-        this.insectBottom = insectBottom;
-        return this;
-    }
-}
diff --git a/src/main/ui/widgets/LogTableModel.java b/src/main/ui/widgets/LogTableModel.java
deleted file mode 100644
index dc7dcbd..0000000
--- a/src/main/ui/widgets/LogTableModel.java
+++ /dev/null
@@ -1,79 +0,0 @@
-package ui.widgets;
-
-import model.ca.AuditLogEntry;
-import model.ca.CertificationAuthority;
-
-import javax.swing.table.AbstractTableModel;
-import java.time.format.DateTimeFormatter;
-import java.util.List;
-
-/**
- * Table model that displays audit logs.
- */
-public class LogTableModel extends AbstractTableModel {
-    /**
-     * Columns
-     */
-    private static final String[] COLS = new String[] {
-            "Time",
-            "Operator",
-            "Action"
-    };
-
-    /**
-     * Pointer to the {@link CertificationAuthority#getLogs()}.
-     */
-    private List<AuditLogEntry> ptrData;
-
-    /**
-     * EFFECTS: Set the pointer to templates
-     * MODIFIES: this
-     */
-    public void setPtrData(List<AuditLogEntry> ptrData) {
-        this.ptrData = ptrData;
-    }
-
-    /**
-     * EFFECT: Return number of rows.
-     */
-    @Override
-    public int getRowCount() {
-        return ptrData == null ? 0 : ptrData.size();
-    }
-
-    /**
-     * EFFECT: Return number of columns.
-     */
-    @Override
-    public int getColumnCount() {
-        return COLS.length;
-    }
-
-    /**
-     * EFFECTS: Get column name.
-     * REQUIRES: column in [9, getColumnCount())
-     */
-    @Override
-    public String getColumnName(int column) {
-        return COLS[column];
-    }
-
-    /**
-     * EFFECTS: Return the value for a cell:
-     *          String (Time)
-     *          String (Operator)
-     *          String (Action)
-     *          Throws {@link IllegalArgumentException} if columnIndex is not in 0 ~ 2
-     * REQUIRES: rowIndex must in range.
-     */
-    @Override
-    public Object getValueAt(int rowIndex, int columnIndex) {
-        final AuditLogEntry e = ptrData.get(rowIndex);
-        switch (columnIndex) {
-            case 0: return e.getTime().format(DateTimeFormatter.ISO_LOCAL_DATE_TIME);
-            case 1: return e.getUser();
-            case 2: return e.getAction();
-            default: throw new IllegalArgumentException();
-        }
-    }
-}
diff --git a/src/main/ui/widgets/QRPanel.java b/src/main/ui/widgets/QRPanel.java
deleted file mode 100644
index d72d0d0..0000000
--- a/src/main/ui/widgets/QRPanel.java
+++ /dev/null
@@ -1,77 +0,0 @@
-package ui.widgets;
-
-import com.google.zxing.BarcodeFormat;
-import com.google.zxing.WriterException;
-import com.google.zxing.common.BitMatrix;
-import com.google.zxing.qrcode.QRCodeWriter;
-
-import javax.swing.*;
-import java.awt.*;
-import java.util.Collections;
-
-import static com.google.zxing.EncodeHintType.ERROR_CORRECTION;
-import static com.google.zxing.qrcode.decoder.ErrorCorrectionLevel.L;
-
-/**
- * A fixed-size panel displaying a QR code.
- */
-public class QRPanel extends JPanel {
-    private final int size;
-
-    private BitMatrix data;
-
-    /**
-     * EFFECTS: Init with the specific rectangular size. Min size = max size = preferred size.
-     */
-    public QRPanel(int size) {
-        super();
-        setSize(new Dimension(size, size));
-        setMaximumSize(new Dimension(size, size));
-        setMinimumSize(new Dimension(size, size));
-        setPreferredSize(new Dimension(size, size));
-        this.size = size;
-    }
-
-    /**
-     * EFFECTS: Draw the QR code. Leave white if no data is set.
-     * MODIFIES: this
-     */
-    @Override
-    protected void paintComponent(Graphics graphics) {
-        super.paintComponent(graphics);
-        graphics.setColor(Color.WHITE);
-        graphics.fillRect(0, 0, size, size);
-
-        if (data == null) {
-            return;
-        }
-
-        graphics.setColor(Color.BLACK);
-        for (int i = 0; i < size; i++) {
-            for (int j = 0; j < size; j++) {
-                if (data.get(i, j)) {
-                    graphics.fillRect(i, j, 1, 1);
-                }
-            }
-        }
-    }
-
-    /**
-     * EFFECTS: Set data and repaint. Nullable.
-     * MODIFIES: this
-     */
-    public void setData(String data) {
-        if (data == null) {
-            this.data = null;
-            invalidate();
-            return;
-        }
-        try {
-            this.data = new QRCodeWriter().encode(data, BarcodeFormat.QR_CODE, size, size,
-                    Collections.singletonMap(ERROR_CORRECTION, L));
-        } catch (WriterException e) {
-            e.printStackTrace();
-        }
-        invalidate();
-    }
-}
diff --git a/src/main/ui/widgets/TemplateTableModel.java b/src/main/ui/widgets/TemplateTableModel.java
deleted file mode 100644
index da4557f..0000000
--- a/src/main/ui/widgets/TemplateTableModel.java
+++ /dev/null
@@ -1,105 +0,0 @@
-package ui.widgets;
-
-import model.ca.CertificationAuthority;
-import model.ca.Template;
-
-import javax.swing.*;
-import javax.swing.table.AbstractTableModel;
-import java.util.List;
-
-/**
- * Table model that displays templates.
- */
-public class TemplateTableModel extends AbstractTableModel {
-    /**
-     * Template enabled icon, same as toolbar enable icon.
-     */
-    private static final ImageIcon ICON_ENABLED =
-            new ImageIcon(TemplateTableModel.class.getResource("/enable.png"));
-
-    /**
-     * Template disbled icon, same as toolbar enable icon.
-     */
-    private static final ImageIcon ICON_DISABLED =
-            new ImageIcon(TemplateTableModel.class.getResource("/disable.png"));
-
-    /**
-     * Columns
-     */
-    private static final String[] COLS = new String[] {
-            "", // Icon
-            "Name",
-            "Subject",
-            "Validity"
-    };
-
-    /**
-     * Pointer to the {@link CertificationAuthority#getTemplates()}.
-     */
-    private List<Template> ptrData;
-
-    /**
-     * EFFECTS: Set the pointer to templates
-     * MODIFIES: this
-     */
-    public void setPtrData(List<Template> ptrData) {
-        this.ptrData = ptrData;
-    }
-
-    /**
-     * EFFECT: Return number of rows.
-     * REQUIRES: column in [9, getColumnCount())
-     */
-    @Override
-    public int getRowCount() {
-        return ptrData == null ? 0 : ptrData.size();
-    }
-
-    /**
-     * EFFECT: Return number of rows.
-     */
-    @Override
-    public int getColumnCount() {
-        return COLS.length;
-    }
-
-    /**
-     * EFFECTS: Get column name.
-     */
-    @Override
-    public String getColumnName(int column) {
-        return COLS[column];
-    }
-
-    /**
-     * EFFECTS: Return the value for a cell:
-     *          ImageIcon (Enabled / Disabled)
-     *          String (Name)
-     *          String (Subject or Not Set)
-     *          String (xx days)
-     *          Throws {@link IllegalArgumentException} if columnIndex is not in 0 ~ 3
-     * REQUIRES: rowIndex must in range.
-     */
-    @Override
-    public Object getValueAt(int rowIndex, int columnIndex) {
-        final Template e = ptrData.get(rowIndex);
-        switch (columnIndex) {
-            case 0: return e.isEnabled() ? ICON_ENABLED : ICON_DISABLED;
-            case 1: return e.getName();
-            case 2: return e.getSubject() == null ? "<Not Set>" : e.getSubject().toString();
-            case 3: return String.format("%d days", e.getValidity());
-            default: throw new IllegalArgumentException();
-        }
-    }
-
-    /**
-     * EFFECTS: Return ImageIcon for 0, String otherwise.
-     */
-    @Override
-    public Class<?> getColumnClass(int columnIndex) {
-        switch (columnIndex) {
-            case 0: return ImageIcon.class;
-            default: return String.class;
-        }
-    }
-}
diff --git a/src/main/ui/widgets/UIUtils.java b/src/main/ui/widgets/UIUtils.java
deleted file mode 100644
index 4442be3..0000000
--- a/src/main/ui/widgets/UIUtils.java
+++ /dev/null
@@ -1,168 +0,0 @@
-package ui.widgets;
-
-import model.asn1.exceptions.ParseException;
-import ui.Utils;
-
-import javax.swing.*;
-import javax.swing.filechooser.FileNameExtensionFilter;
-import java.awt.*;
-import java.awt.event.ActionListener;
-import java.io.IOException;
-import java.io.InputStream;
-import java.nio.file.Files;
-import java.nio.file.Path;
-import java.nio.file.Paths;
-import java.nio.file.StandardOpenOption;
-import java.util.stream.IntStream;
-
-import static java.awt.GridBagConstraints.BOTH;
-import static java.awt.GridBagConstraints.HORIZONTAL;
-import static javax.swing.JOptionPane.*;
-
-/**
- * Useful utilities for building GUI.
- */
-public class UIUtils {
-    /**
-     * EFFECTS: Create a horizontal actions pane:
-     * -----------------------------------------------------------
-     * |                 | Button1 | Button2 | Button3 | ButtonN |
-     * -----------------------------------------------------------
-     * REQUIRES: buttons != null
-     */
-    public static JPanel createActionsPane(JButton... buttons) {
-        final JPanel panelAct = new JPanel();
-        panelAct.setLayout(new GridBagLayout());
-        IntStream.range(0, buttons.length)
-                .forEach(i -> panelAct.add(buttons[i],
-                        new GCBuilder().gridXY(i + 1, 1).fill(HORIZONTAL).build()));
-        panelAct.add(new JPanel(), new GCBuilder().expandXY().fill(BOTH).build());
-        return panelAct;
-    }
-
-    /**
-     * EFFECTS: Show / hide default text for a card layout container.
-     * MODIFIES: cardLayoutPanel
-     * REQUIRES: cardLayoutPanel must have a card layout; it must have CardContent and CardDefault cards.
-     */
-    public static void setContentVisible(Container cardLayoutPanel, boolean showContent) {
-        switchTo(cardLayoutPanel, showContent ? "CardContent" : "CardDefault");
-    }
-
-    /**
-     * EFFECTS: Switch to the card for a card layout panel.
-     * MODIFIES: cardLayoutPanel
-     * REQUIRES: cardLayoutPanel must have a card layout; it must have "card" card.
-     */
-    public static void switchTo(Container cardLayoutPanel, String card) {
-        ((CardLayout) cardLayoutPanel.getLayout()).show(cardLayoutPanel, card);
-    }
-
-    /**
-     * EFFECTS: Show an error message based on {@link Throwable#getMessage()}
-     * REQUIRES: component must have a frame.
-     */
-    public static void alert(Component component, String title, Throwable e) {
-        alert(component, title, e.getMessage());
-    }
-
-    /**
-     * EFFECTS: Show an error message.
-     * REQUIRES: component must have a frame.
-     */
-    public static void alert(Component component, String title, String message) {
-        showMessageDialog(getFrameForComponent(component),
-                message,
-                title,
-                ERROR_MESSAGE);
-    }
-
-    /**
-     * EFFECTS: Show a file chooser with the given filter title and list of extensions. Starting from cwd.
-     * Return null if cancelled.
-     */
-    public static Path chooseFile(Component component, String filterTitle, String... extensions) {
-        final JFileChooser fc = new JFileChooser();
-        fc.setFileFilter(new FileNameExtensionFilter(filterTitle, extensions));
-        fc.setCurrentDirectory(Paths.get("").toAbsolutePath().toFile());
-        if (fc.showOpenDialog(getFrameForComponent(component)) == JFileChooser.APPROVE_OPTION) {
-            return fc.getSelectedFile().toPath();
-        }
-        return null;
-    }
-
-    /**
-     * EFFECTS: Create a JPanel with CardLayout that has CardDefault set to component and CardContent set to a JLabel
-     * with the default text.
-     */
-    public static JPanel defView(Component component, String defaultText) {
-        final JPanel panel = new JPanel();
-        panel.setLayout(new CardLayout(0, 0));
-
-        JLabel labelDefault = new JLabel(defaultText);
-        labelDefault.setHorizontalAlignment(0);
-        panel.add(labelDefault, "CardDefault");
-        panel.add(component, "CardContent");
-
-        return panel;
-    }
-
-    /**
-     * EFFECTS: Create a JScrollPane-wrapped JTable.
-     * MODIFIES: table
-     */
-    public static JScrollPane scrTbl(JTable table) {
-        final JScrollPane scrollPane = new JScrollPane();
-        table.setFillsViewportHeight(true);
-        scrollPane.setViewportView(table);
-        return scrollPane;
-    }
-
-    /**
-     * EFFECTS: Parse the given path and automatically determine if it is a DER binary or a PEM. Automatically decode
-     * PEM.
-     *      Throws {@link IOException} if it cannot be read.
-     *      Throws {@link ParseException} if the PEM is invalid.
-     */
-    public static Byte[] openDERorPEM(Path path, String tag) throws IOException, ParseException {
-        final InputStream fd = Files.newInputStream(path, StandardOpenOption.READ);
-        Byte[] bs = Utils.byteToByte(fd.readAllBytes());
-        fd.close();
-        if (bs.length < 1) {
-            throw new ParseException("Invalid file: too short");
-        }
-        if (bs[0] == '-') {
-            bs = Utils.parsePEM(bs, tag);
-        }
-        return bs;
-    }
-
-    /**
-     * EFFECTS: Create a button with the given label and click listener.
-     */
-    public static JButton btn(String string, ActionListener onClick) {
-        final JButton btn = new JButton(string);
-        btn.addActionListener(onClick);
-        return btn;
-    }
-
-    /**
-     * EFFECTS: Create a button with the given label, mnemonic, and click listener.
-     */
-    public static JButton btn(String string, char m, ActionListener onClick) {
-        final JButton btn = new JButton(string);
-        btn.setMnemonic(m);
-        btn.setDisplayedMnemonicIndex(0);
-        btn.addActionListener(onClick);
-        return btn;
-    }
-
-    /**
-     * EFFECTS: Create a button with the given label, mnemonic, icon, and click listener.
-     */
-    public static JButton btn(String string, String icon, ActionListener onClick) {
-        final JButton btn = new JButton(string, new ImageIcon(UIUtils.class.getResource("/" + icon)));
-        btn.addActionListener(onClick);
-        return btn;
-    }
-}
-- 
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