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, 53 insertions, 0 deletions

diff --git a/src/main/model/asn1/IA5String.java b/src/main/model/asn1/IA5String.java
new file mode 100644
index 0000000..ea5cf91
--- /dev/null
+++ b/src/main/model/asn1/IA5String.java
@@ -0,0 +1,53 @@
+package model.asn1;
+
+import model.asn1.exceptions.ParseException;
+import model.asn1.parsing.BytesReader;
+import ui.Utils;
+
+import java.nio.charset.StandardCharsets;
+import java.util.Arrays;
+
+/**
+ * Represents an ASN.1 IA5String type. It is a string that is restricted to ISO 646 / T.50 characters.
+ */
+public class IA5String extends ASN1String {
+    /**
+     * The X.680 universal class tag assignment.
+     */
+    public static final Tag TAG = new Tag(TagClass.UNIVERSAL, false, 0x16);
+
+    /**
+     * EFFECTS: Constructs an IA5String with the given tag and string.
+     *   Throws {@link ParseException} if the string is invalid. It must only contain T.50 chars.
+     * REQUIRES: For the requirements of tag and parentTag, consult {@link ASN1Object}.
+     */
+    public IA5String(Tag tag, Tag parentTag, String string) throws ParseException {
+        super(tag, parentTag, string);
+    }
+
+    /**
+     * EFFECTS: Parse from user input. Tags are parsed as-per {@link ASN1Object}. The value will be parsed as UTF-8 big
+     * endian.
+     *   Throws {@link ParseException} if the encoded data is invalid:
+     *     - Illegal string (containing non-T.50 chars)
+     *     - Early EOF
+     *     - Other cases in {@link ASN1Object}
+     * MODIFIES: this, encoded
+     */
+    public IA5String(BytesReader encoded, boolean hasParentTag) throws ParseException {
+        super(encoded, hasParentTag);
+        setString(new String(Utils.byteToByte(encoded.require(getLength(), true)),
+                StandardCharsets.UTF_8));
+    }
+
+    /**
+     * EFFECTS: Checks whether the given string only contains ISO 646 / T.50 chars.
+     */
+    @Override
+    protected boolean validate(String newString) {
+        // Java doesn't have unsigned bytes - that is, bytes greater than 0x7F will
+        // overflow and become < 0. Thus, just compare b >= 0 will suffice.
+        return Arrays.stream(Utils.byteToByte(newString.getBytes(StandardCharsets.UTF_8)))
+                .noneMatch(b -> b < 0);
+    }
+}