1 files changed, 231 insertions, 0 deletions
diff --git a/core/src/main/java/org/spongycastle/crypto/macs/HMac.java b/core/src/main/java/org/spongycastle/crypto/macs/HMac.java
new file mode 100644
index 00000000..e7c0fe56
--- /dev/null
+++ b/core/src/main/java/org/spongycastle/crypto/macs/HMac.java
@@ -0,0 +1,231 @@
+package org.spongycastle.crypto.macs;
+
+import java.util.Hashtable;
+
+import org.spongycastle.crypto.CipherParameters;
+import org.spongycastle.crypto.Digest;
+import org.spongycastle.crypto.ExtendedDigest;
+import org.spongycastle.crypto.Mac;
+import org.spongycastle.crypto.params.KeyParameter;
+import org.spongycastle.util.Integers;
+import org.spongycastle.util.Memoable;
+
+/**
+ * HMAC implementation based on RFC2104
+ *
+ * H(K XOR opad, H(K XOR ipad, text))
+ */
+public class HMac
+    implements Mac
+{
+    private final static byte IPAD = (byte)0x36;
+    private final static byte OPAD = (byte)0x5C;
+
+    private Digest digest;
+    private int digestSize;
+    private int blockLength;
+    private Memoable ipadState;
+    private Memoable opadState;
+
+    private byte[] inputPad;
+    private byte[] outputBuf;
+
+    private static Hashtable blockLengths;
+    
+    static
+    {
+        blockLengths = new Hashtable();
+        
+        blockLengths.put("GOST3411", Integers.valueOf(32));
+        
+        blockLengths.put("MD2", Integers.valueOf(16));
+        blockLengths.put("MD4", Integers.valueOf(64));
+        blockLengths.put("MD5", Integers.valueOf(64));
+        
+        blockLengths.put("RIPEMD128", Integers.valueOf(64));
+        blockLengths.put("RIPEMD160", Integers.valueOf(64));
+        
+        blockLengths.put("SHA-1", Integers.valueOf(64));
+        blockLengths.put("SHA-224", Integers.valueOf(64));
+        blockLengths.put("SHA-256", Integers.valueOf(64));
+        blockLengths.put("SHA-384", Integers.valueOf(128));
+        blockLengths.put("SHA-512", Integers.valueOf(128));
+        
+        blockLengths.put("Tiger", Integers.valueOf(64));
+        blockLengths.put("Whirlpool", Integers.valueOf(64));
+    }
+    
+    private static int getByteLength(
+        Digest digest)
+    {
+        if (digest instanceof ExtendedDigest)
+        {
+            return ((ExtendedDigest)digest).getByteLength();
+        }
+        
+        Integer  b = (Integer)blockLengths.get(digest.getAlgorithmName());
+        
+        if (b == null)
+        {       
+            throw new IllegalArgumentException("unknown digest passed: " + digest.getAlgorithmName());
+        }
+        
+        return b.intValue();
+    }
+    
+    /**
+     * Base constructor for one of the standard digest algorithms that the 
+     * byteLength of the algorithm is know for.
+     * 
+     * @param digest the digest.
+     */
+    public HMac(
+        Digest digest)
+    {
+        this(digest, getByteLength(digest));
+    }
+
+    private HMac(
+        Digest digest,
+        int    byteLength)
+    {
+        this.digest = digest;
+        this.digestSize = digest.getDigestSize();
+        this.blockLength = byteLength;
+        this.inputPad = new byte[blockLength];
+        this.outputBuf = new byte[blockLength + digestSize];
+    }
+
+    public String getAlgorithmName()
+    {
+        return digest.getAlgorithmName() + "/HMAC";
+    }
+
+    public Digest getUnderlyingDigest()
+    {
+        return digest;
+    }
+
+    public void init(
+        CipherParameters params)
+    {
+        digest.reset();
+
+        byte[] key = ((KeyParameter)params).getKey();
+        int keyLength = key.length;
+
+        if (keyLength > blockLength)
+        {
+            digest.update(key, 0, keyLength);
+            digest.doFinal(inputPad, 0);
+            
+            keyLength = digestSize;
+        }
+        else
+        {
+            System.arraycopy(key, 0, inputPad, 0, keyLength);
+        }
+
+        for (int i = keyLength; i < inputPad.length; i++)
+        {
+            inputPad[i] = 0;
+        }
+
+        System.arraycopy(inputPad, 0, outputBuf, 0, blockLength);
+
+        xorPad(inputPad, blockLength, IPAD);
+        xorPad(outputBuf, blockLength, OPAD);
+
+        if (digest instanceof Memoable)
+        {
+            opadState = ((Memoable)digest).copy();
+
+            ((Digest)opadState).update(outputBuf, 0, blockLength);
+        }
+
+        digest.update(inputPad, 0, inputPad.length);
+
+        if (digest instanceof Memoable)
+        {
+            ipadState = ((Memoable)digest).copy();
+        }
+    }
+
+    public int getMacSize()
+    {
+        return digestSize;
+    }
+
+    public void update(
+        byte in)
+    {
+        digest.update(in);
+    }
+
+    public void update(
+        byte[] in,
+        int inOff,
+        int len)
+    {
+        digest.update(in, inOff, len);
+    }
+
+    public int doFinal(
+        byte[] out,
+        int outOff)
+    {
+        digest.doFinal(outputBuf, blockLength);
+
+        if (opadState != null)
+        {
+            ((Memoable)digest).reset(opadState);
+            digest.update(outputBuf, blockLength, digest.getDigestSize());
+        }
+        else
+        {
+            digest.update(outputBuf, 0, outputBuf.length);
+        }
+
+        int len = digest.doFinal(out, outOff);
+
+        for (int i = blockLength; i < outputBuf.length; i++)
+        {
+            outputBuf[i] = 0;
+        }
+
+        if (ipadState != null)
+        {
+            ((Memoable)digest).reset(ipadState);
+        }
+        else
+        {
+            digest.update(inputPad, 0, inputPad.length);
+        }
+
+        return len;
+    }
+
+    /**
+     * Reset the mac generator.
+     */
+    public void reset()
+    {
+        /*
+         * reset the underlying digest.
+         */
+        digest.reset();
+
+        /*
+         * reinitialize the digest.
+         */
+        digest.update(inputPad, 0, inputPad.length);
+    }
+
+    private static void xorPad(byte[] pad, int len, byte n)
+    {
+        for (int i = 0; i < len; ++i)
+        {
+            pad[i] ^= n;
+        }
+    }
+}