1 files changed, 182 insertions, 0 deletions
diff --git a/src/org/xbill/DNS/utils/HMAC.java b/src/org/xbill/DNS/utils/HMAC.java
new file mode 100644
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--- /dev/null
+++ b/src/org/xbill/DNS/utils/HMAC.java
@@ -0,0 +1,182 @@
+// Copyright (c) 1999-2004 Brian Wellington (bwelling@xbill.org)
+
+package org.xbill.DNS.utils;
+
+import java.util.Arrays;
+import java.security.*;
+
+/**
+ * An implementation of the HMAC message authentication code.
+ *
+ * @author Brian Wellington
+ */
+
+public class HMAC {
+
+private MessageDigest digest;
+private int blockLength;
+
+private byte [] ipad, opad;
+
+private static final byte IPAD = 0x36;
+private static final byte OPAD = 0x5c;
+
+private void
+init(byte [] key) {
+	int i;
+
+	if (key.length > blockLength) {
+		key = digest.digest(key);
+		digest.reset();
+	}
+	ipad = new byte[blockLength];
+	opad = new byte[blockLength];
+	for (i = 0; i < key.length; i++) {
+		ipad[i] = (byte) (key[i] ^ IPAD);
+		opad[i] = (byte) (key[i] ^ OPAD);
+	}
+	for (; i < blockLength; i++) {
+		ipad[i] = IPAD;
+		opad[i] = OPAD;
+	}
+	digest.update(ipad);
+}
+
+/**
+ * Creates a new HMAC instance
+ * @param digest The message digest object.
+ * @param blockLength The block length of the message digest.
+ * @param key The secret key
+ */
+public
+HMAC(MessageDigest digest, int blockLength, byte [] key) {
+	digest.reset();
+	this.digest = digest;
+  	this.blockLength = blockLength;
+	init(key);
+}
+
+/**
+ * Creates a new HMAC instance
+ * @param digestName The name of the message digest function.
+ * @param blockLength The block length of the message digest.
+ * @param key The secret key.
+ */
+public
+HMAC(String digestName, int blockLength, byte [] key) {
+	try {
+		digest = MessageDigest.getInstance(digestName);
+	} catch (NoSuchAlgorithmException e) {
+		throw new IllegalArgumentException("unknown digest algorithm "
+						   + digestName);
+	}
+	this.blockLength = blockLength;
+	init(key);
+}
+
+/**
+ * Creates a new HMAC instance
+ * @param digest The message digest object.
+ * @param key The secret key
+ * @deprecated won't work with digests using a padding length other than 64;
+ *             use {@code HMAC(MessageDigest digest, int blockLength,
+ *             byte [] key)} instead.
+ * @see        HMAC#HMAC(MessageDigest digest, int blockLength, byte [] key)
+ */
+public
+HMAC(MessageDigest digest, byte [] key) {
+	this(digest, 64, key);
+}
+
+/**
+ * Creates a new HMAC instance
+ * @param digestName The name of the message digest function.
+ * @param key The secret key.
+ * @deprecated won't work with digests using a padding length other than 64;
+ *             use {@code HMAC(String digestName, int blockLength, byte [] key)}
+ *             instead
+ * @see        HMAC#HMAC(String digestName, int blockLength, byte [] key)
+ */
+public
+HMAC(String digestName, byte [] key) {
+	this(digestName, 64, key);
+}
+
+/**
+ * Adds data to the current hash
+ * @param b The data
+ * @param offset The index at which to start adding to the hash
+ * @param length The number of bytes to hash
+ */
+public void
+update(byte [] b, int offset, int length) {
+	digest.update(b, offset, length);
+}
+
+/**
+ * Adds data to the current hash
+ * @param b The data
+ */
+public void
+update(byte [] b) {
+	digest.update(b);
+}
+
+/**
+ * Signs the data (computes the secure hash)
+ * @return An array with the signature
+ */
+public byte []
+sign() {
+	byte [] output = digest.digest();
+	digest.reset();
+	digest.update(opad);
+	return digest.digest(output);
+}
+
+/**
+ * Verifies the data (computes the secure hash and compares it to the input)
+ * @param signature The signature to compare against
+ * @return true if the signature matches, false otherwise
+ */
+public boolean
+verify(byte [] signature) {
+	return verify(signature, false);
+}
+
+/**
+ * Verifies the data (computes the secure hash and compares it to the input)
+ * @param signature The signature to compare against
+ * @param truncation_ok If true, the signature may be truncated; only the
+ * number of bytes in the provided signature are compared.
+ * @return true if the signature matches, false otherwise
+ */
+public boolean
+verify(byte [] signature, boolean truncation_ok) {
+	byte [] expected = sign();
+	if (truncation_ok && signature.length < expected.length) {
+		byte [] truncated = new byte[signature.length];
+		System.arraycopy(expected, 0, truncated, 0, truncated.length);
+		expected = truncated;
+	}
+	return Arrays.equals(signature, expected);
+}
+
+/**
+ * Resets the HMAC object for further use
+ */
+public void
+clear() {
+	digest.reset();
+	digest.update(ipad);
+}
+
+/**
+ * Returns the length of the digest.
+ */
+public int
+digestLength() {
+	return digest.getDigestLength();
+}
+
+}