1 files changed, 45 insertions, 0 deletions
diff --git a/src/main/model/asn1/Null.java b/src/main/model/asn1/Null.java
new file mode 100644
index 0000000..019db85
--- /dev/null
+++ b/src/main/model/asn1/Null.java
@@ -0,0 +1,45 @@
+package model.asn1;
+
+import model.asn1.exceptions.ParseException;
+import model.asn1.parsing.BytesReader;
+
+/**
+ * Represents the ASN.1 NULL type. It always has zero length. With the default assigned tag, it always encodes
+ * into 0x05 0x00.
+ */
+public class Null extends ASN1Object {
+    /**
+     * The X.680 universal class tag assignment.
+     */
+    public static final Tag TAG = new Tag(TagClass.UNIVERSAL, false, 0x5);
+
+    /**
+     * EFFECTS: Initiate the NULL with the given tag and an optional context-specific tag number for explicit
+     * encoding. For more information, consult {@link ASN1Object}. NULL does not take any other arguments.
+     * REQUIRES: Consult {@link ASN1Object}.
+     */
+    public Null(Tag tag, Tag parentTag) {
+        super(tag, parentTag);
+    }
+
+    /**
+     * EFFECTS: Parse input bytes. For more information on tags parsing, consult {@link ASN1Object}.
+     *   Throws {@link ParseException} if the input data is invalid:
+     *     - The length is not 0
+     *     - Other cases as denoted in {@link ASN1Object}
+     */
+    public Null(BytesReader encoded, boolean hasParentTag) throws ParseException {
+        super(encoded, hasParentTag);
+        if (getLength() != 0) {
+            throw new ParseException("NULL must have zero length!");
+        }
+    }
+
+    /**
+     * EFFECTS: Always produce an empty array.
+     */
+    @Override
+    public Byte[] encodeValueDER() {
+        return new Byte[0];
+    }
+}