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, 66 insertions, 0 deletions

diff --git a/src/main/model/asn1/ASN1Time.java b/src/main/model/asn1/ASN1Time.java
new file mode 100644
index 0000000..08f861e
--- /dev/null
+++ b/src/main/model/asn1/ASN1Time.java
@@ -0,0 +1,66 @@
+package model.asn1;
+
+import model.asn1.exceptions.ParseException;
+import model.asn1.parsing.BytesReader;
+import ui.Utils;
+
+import java.nio.charset.StandardCharsets;
+import java.time.ZonedDateTime;
+
+/**
+ * Common base-class for models like UTCTime and GeneralizedTime. Despite all the formatting and encoding differences,
+ * it stores a timestamp and corresponding timezone.
+ */
+public abstract class ASN1Time extends ASN1Object {
+    /**
+     * The time.
+     */
+    private ZonedDateTime timestamp;
+
+    /**
+     * EFFECTS: Initialize the time with the specific tag, parentTag, and timestamp. For tag and parentTag, consult
+     * {@link ASN1Object}.
+     */
+    public ASN1Time(Tag tag, Tag parentTag, ZonedDateTime timestamp) {
+        super(tag, parentTag);
+        this.timestamp = timestamp;
+    }
+
+    /**
+     * EFFECTS: Parse and decode DER bytes into the corresponding time type. For more info on decoding, take a look at
+     * {@link ASN1Object}.
+     *   Throws {@link ParseException} if the input is invalid:
+     *    - Invalid date format
+     *    - Zero length
+     *    - Other circumstances (e.g., early EOF) as seen in {@link ASN1Object}
+     * MODIFIES: this, encoded
+     */
+    public ASN1Time(BytesReader encoded, boolean hasParentTag) throws ParseException {
+        super(encoded, hasParentTag);
+        this.timestamp = toDate(new String(Utils.byteToByte(encoded.require(getLength(), true))));
+    }
+
+    /**
+     * EFFECTS: Generate the byte array for the formatted string.
+     */
+    @Override
+    public Byte[] encodeValueDER() {
+        return Utils.byteToByte(toString().getBytes(StandardCharsets.UTF_8));
+    }
+
+    /**
+     * EFFECTS: Convert the given string into corresponding timestamp.
+     *   Throws {@link ParseException} if the time is malformed.
+     */
+    public abstract ZonedDateTime toDate(String str) throws ParseException;
+
+    /**
+     * EFFECTS: Convert getTimestamp() into corresponding ASN.1 time format.
+     */
+    @Override
+    public abstract String toString();
+
+    public ZonedDateTime getTimestamp() {
+        return timestamp;
+    }
+}