--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/ch/ethz/ssh2/crypto/digest/HMAC.java	Fri Jul 18 11:21:46 2014 -0700
@@ -0,0 +1,97 @@
+/*
+ * Copyright (c) 2006-2011 Christian Plattner. All rights reserved.
+ * Please refer to the LICENSE.txt for licensing details.
+ */
+package ch.ethz.ssh2.crypto.digest;
+
+import java.security.DigestException;
+
+/**
+ * HMAC.
+ * 
+ * @author Christian Plattner
+ * @version 2.50, 03/15/10
+ */
+public final class HMAC implements Digest
+{
+	Digest md;
+	byte[] k_xor_ipad;
+	byte[] k_xor_opad;
+
+	byte[] tmp;
+
+	int size;
+
+	public HMAC(Digest md, byte[] key, int size) throws DigestException {
+		this.md = md;
+		this.size = size;
+
+		tmp = new byte[md.getDigestLength()];
+
+		final int BLOCKSIZE = 64;
+
+		k_xor_ipad = new byte[BLOCKSIZE];
+		k_xor_opad = new byte[BLOCKSIZE];
+
+		if (key.length > BLOCKSIZE)
+		{
+			md.reset();
+			md.update(key);
+			md.digest(tmp);
+			key = tmp;
+		}
+
+		System.arraycopy(key, 0, k_xor_ipad, 0, key.length);
+		System.arraycopy(key, 0, k_xor_opad, 0, key.length);
+
+		for (int i = 0; i < BLOCKSIZE; i++)
+		{
+			k_xor_ipad[i] ^= 0x36;
+			k_xor_opad[i] ^= 0x5C;
+		}
+		md.update(k_xor_ipad);
+	}
+
+	public final int getDigestLength()
+	{
+		return size;
+	}
+
+	public final void update(byte b)
+	{
+		md.update(b);
+	}
+
+	public final void update(byte[] b)
+	{
+		md.update(b);
+	}
+
+	public final void update(byte[] b, int off, int len)
+	{
+		md.update(b, off, len);
+	}
+
+	public final void reset()
+	{
+		md.reset();
+		md.update(k_xor_ipad);
+	}
+
+	public final void digest(byte[] out) throws DigestException {
+		digest(out, 0);
+	}
+
+	public final void digest(byte[] out, int off) throws DigestException {
+		md.digest(tmp);
+
+		md.update(k_xor_opad);
+		md.update(tmp);
+
+		md.digest(tmp);
+
+		System.arraycopy(tmp, 0, out, off, size);
+
+		md.update(k_xor_ipad);
+	}
+}