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))
/** * 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.
Params:
  • digest – the digest.
/** * 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.
/** * Reset the mac generator. */
public void reset() { /* * reset the underlying digest. */ digest.reset(); /* * reinitialize the digest. */ digest.update(inputPad, 0, inputPad.length); } }