Implement data structures from X.680, X.501, X.509, and PKCS#10, with X.690 encoding / decoding support

The implementation took four days, and it is still a little bit rough. Updated version should arrive soon.

Signed-off-by: Yuuta Liang <yuutaw@students.cs.ubc.ca>

1 files changed, 85 insertions, 0 deletions

diff --git a/src/main/model/asn1/ASN1String.java b/src/main/model/asn1/ASN1String.java
new file mode 100644
index 0000000..148c564
--- /dev/null
+++ b/src/main/model/asn1/ASN1String.java
@@ -0,0 +1,85 @@
+package model.asn1;
+
+import model.asn1.exceptions.ParseException;
+import model.asn1.parsing.BytesReader;
+import ui.Utils;
+
+import java.nio.charset.StandardCharsets;
+
+/**
+ * Represents an ASN.1 string with an optional character set restriction. Users should choose from one of its
+ * implementations that encode a specific ASN.1 string type (e.g., {@link PrintableString} or {@link IA5String}).
+ */
+public abstract class ASN1String extends ASN1Object {
+    private String rawString;
+
+    /**
+     * EFFECTS: Constructs an ASN1String with the given tag, parent tag, and string.
+     *   - Throws {@link ParseException} if the string does not pass corresponding restrictions of the specific
+     *   string type (same as {@link ASN1String#validate(String)})
+     * REQUIRES: For the requirements of tag and parentTag, consult {@link ASN1Object}.
+     */
+    public ASN1String(Tag tag, Tag parentTag, String string) throws ParseException {
+        super(tag, parentTag);
+        setString(string);
+    }
+
+    /**
+     * EFFECTS: Parse the input value. See {@link ASN1Object} with the rawString.
+     *   Throws {@link ParseException} when invalid:
+     *     - String does not pass type restrictions
+     *     - Early EOF
+     *     - Other cases as seen in {@link ASN1Object}
+     * MODIFIES: this, encoded (bytes are read)
+     */
+    public ASN1String(BytesReader encoded, boolean hasParentTag) throws ParseException {
+        super(encoded, hasParentTag);
+    }
+
+    /**
+     * EFFECTS: Validate and set the string.
+     *   Throws {@link ParseException} if the string is invalid.
+     * MODIFIES: this
+     */
+    protected void setString(String rawString) throws ParseException {
+        if (!validate(rawString)) {
+            throw new ParseException(String.format("The string '%s' is illegal for '%s'.",
+                    rawString,
+                    getClass().getSimpleName()));
+        }
+        this.rawString = rawString;
+    }
+
+    /**
+     * EFFECTS: Validate whether the given string matches the ASN.1 restrictions on this specific string type. By
+     * default, it always returns true.
+     */
+    protected boolean validate(String newString) {
+        return true;
+    }
+
+    /**
+     * Same as {@link ASN1String#getString()}.
+     */
+    @Override
+    public String toString() {
+        return rawString;
+    }
+
+    /**
+     * EFFECTS: Encode the string in DER bytes (big-endian UTF-8).
+     */
+    @Override
+    public Byte[] encodeValueDER() {
+        final byte[] bytes = rawString.getBytes(StandardCharsets.UTF_8);
+        Byte[] b = new Byte[bytes.length];
+        for (int i = 0; i < bytes.length; i++) {
+            b[i] = bytes[i];
+        }
+        return b;
+    }
+
+    public String getString() {
+        return rawString;
+    }
+}