From 4d903cf80c4f2f8a5d6b22964ed23d8584fdbed4 Mon Sep 17 00:00:00 2001
From: Yuuta Liang <yuutaw@student.cs.ubc.ca>
Date: Thu, 23 Nov 2023 08:41:56 +0800
Subject: Add QR code

Signed-off-by: Yuuta Liang <yuutaw@student.cs.ubc.ca>
---
 README.md                        |  3 ++
 src/main/ui/MainUI.java          | 16 ++++++++-
 src/main/ui/widgets/QRPanel.java | 77 ++++++++++++++++++++++++++++++++++++++++
 3 files changed, 95 insertions(+), 1 deletion(-)
 create mode 100644 src/main/ui/widgets/QRPanel.java

diff --git a/README.md b/README.md
index 1040e4b..802448a 100644
--- a/README.md
+++ b/README.md
@@ -85,6 +85,9 @@ container, upon each successful sign.
 8. Periodically publish CRLs. On the "CA" tab, click on the "CRL" button on the top right, and select a path for the CRL.
    The database automatically saves after issuing a new CRL.
 
+The CA public key will also be rendered as a QR code on the "CA" tab, for easier transfer between computers. The encoded
+data is PEM-encoded PKCS#1 public key.
+
 ## Author
 
 Yuuta Liang <yuutaw@student.ubc.ca>
diff --git a/src/main/ui/MainUI.java b/src/main/ui/MainUI.java
index 9637d79..34cc224 100644
--- a/src/main/ui/MainUI.java
+++ b/src/main/ui/MainUI.java
@@ -92,6 +92,7 @@ public class MainUI extends JFrame {
     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);
 
@@ -192,6 +193,17 @@ public class MainUI extends JFrame {
         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-----
@@ -327,7 +339,8 @@ public class MainUI extends JFrame {
         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(new JPanel(), new GCBuilder().gridXY(3, 3).expandXY().fill(BOTH).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"));
 
@@ -339,6 +352,7 @@ public class MainUI extends JFrame {
      * MODIFIES: this
      */
     private void renderCAPage() {
+        renderQRPublicKey();
         if (ca.getPublicKey() == null) {
             labelPrivateKey.setText("Private key not installed");
         } else {
diff --git a/src/main/ui/widgets/QRPanel.java b/src/main/ui/widgets/QRPanel.java
new file mode 100644
index 0000000..d72d0d0
--- /dev/null
+++ b/src/main/ui/widgets/QRPanel.java
@@ -0,0 +1,77 @@
+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();
+    }
+}
-- 
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