package org.bouncycastle.crypto.macs;import java.util.Hashtable;import org.bouncycastle.crypto.CipherParameters;import org.bouncycastle.crypto.Digest;import org.bouncycastle.crypto.ExtendedDigest;import org.bouncycastle.crypto.Mac;import org.bouncycastle.crypto.params.KeyParameter;/** * 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 byte[] inputPad;    private byte[] outputPad;    private static Hashtable blockLengths;        static    {        blockLengths = new Hashtable();                blockLengths.put("GOST3411", new Integer(32));                blockLengths.put("MD2", new Integer(16));        blockLengths.put("MD4", new Integer(64));        blockLengths.put("MD5", new Integer(64));                blockLengths.put("RIPEMD128", new Integer(64));        blockLengths.put("RIPEMD160", new Integer(64));                blockLengths.put("SHA-1", new Integer(64));        blockLengths.put("SHA-224", new Integer(64));        blockLengths.put("SHA-256", new Integer(64));        blockLengths.put("SHA-384", new Integer(128));        blockLengths.put("SHA-512", new Integer(128));                blockLengths.put("Tiger", new Integer(64));        blockLengths.put("Whirlpool", new Integer(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;        digestSize = digest.getDigestSize();        this.blockLength = byteLength;        inputPad = new byte[blockLength];        outputPad = new byte[blockLength];    }        public String getAlgorithmName()    {        return digest.getAlgorithmName() + "/HMAC";    }    public Digest getUnderlyingDigest()    {        return digest;    }    public void init(        CipherParameters params)    {        digest.reset();        byte[] key = ((KeyParameter)params).getKey();        if (key.length > blockLength)        {            digest.update(key, 0, key.length);            digest.doFinal(inputPad, 0);            for (int i = digestSize; i < inputPad.length; i++)            {                inputPad[i] = 0;            }        }        else        {            System.arraycopy(key, 0, inputPad, 0, key.length);            for (int i = key.length; i < inputPad.length; i++)            {                inputPad[i] = 0;            }        }        outputPad = new byte[inputPad.length];        System.arraycopy(inputPad, 0, outputPad, 0, inputPad.length);        for (int i = 0; i < inputPad.length; i++)        {            inputPad[i] ^= IPAD;        }        for (int i = 0; i < outputPad.length; i++)        {            outputPad[i] ^= OPAD;        }        digest.update(inputPad, 0, inputPad.length);    }    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)    {        byte[] tmp = new byte[digestSize];        digest.doFinal(tmp, 0);        digest.update(outputPad, 0, outputPad.length);        digest.update(tmp, 0, tmp.length);        int     len = digest.doFinal(out, outOff);        reset();        return len;    }    /**     * Reset the mac generator.     */    public void reset()    {        /*         * reset the underlying digest.         */        digest.reset();        /*         * reinitialize the digest.         */        digest.update(inputPad, 0, inputPad.length);    }}