hmac.java

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// Decompiled by Jad v1.5.8e2. Copyright 2001 Pavel Kouznetsov.
// Jad home page: http://kpdus.tripod.com/jad.html
// Decompiler options: packimports(3) fieldsfirst ansi space 
// Source File Name:   HMac.java

package org.bouncycastle.crypto.macs;

import org.bouncycastle.crypto.*;
import org.bouncycastle.crypto.params.KeyParameter;

public class HMac
	implements Mac
{

	private static final int BLOCK_LENGTH = 64;
	private static final byte IPAD = 54;
	private static final byte OPAD = 92;
	private Digest digest;
	private int digestSize;
	private byte inputPad[];
	private byte outputPad[];

	public HMac(Digest digest)
	{
		inputPad = new byte[64];
		outputPad = new byte[64];
		this.digest = digest;
		digestSize = digest.getDigestSize();
	}

	public String getAlgorithmName()
	{
		return (new StringBuilder()).append(digest.getAlgorithmName()).append("/HMAC").toString();
	}

	public Digest getUnderlyingDigest()
	{
		return digest;
	}

	public void init(CipherParameters params)
	{
		digest.reset();
		byte key[] = ((KeyParameter)params).getKey();
		if (key.length > 64)
		{
			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] ^= 0x36;

		for (int i = 0; i < outputPad.length; i++)
			outputPad[i] ^= 0x5c;

		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;
	}

	public void reset()
	{
		digest.reset();
		digest.update(inputPad, 0, inputPad.length);
	}
}