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package org.bouncycastle.crypto.digests;
import org.bouncycastle.crypto.ExtendedDigest;
import org.bouncycastle.util.Memoable;
import org.bouncycastle.util.Pack;
/**
* base implementation of MD4 family style digest as outlined in
* "Handbook of Applied Cryptography", pages 344 - 347.
*/
public abstract class GeneralDigest
implements ExtendedDigest, Memoable
{
private static final int BYTE_LENGTH = 64;
private final byte[] xBuf = new byte[4];
private int xBufOff;
private long byteCount;
/**
* Standard constructor
*/
protected GeneralDigest()
{
xBufOff = 0;
}
/**
* Copy constructor. We are using copy constructors in place
* of the Object.clone() interface as this interface is not
* supported by J2ME.
*/
protected GeneralDigest(GeneralDigest t)
{
copyIn(t);
}
protected GeneralDigest(byte[] encodedState)
{
System.arraycopy(encodedState, 0, xBuf, 0, xBuf.length);
xBufOff = Pack.bigEndianToInt(encodedState, 4);
byteCount = Pack.bigEndianToLong(encodedState, 8);
}
protected void copyIn(GeneralDigest t)
{
System.arraycopy(t.xBuf, 0, xBuf, 0, t.xBuf.length);
xBufOff = t.xBufOff;
byteCount = t.byteCount;
}
public void update(
byte in)
{
xBuf[xBufOff++] = in;
if (xBufOff == xBuf.length)
{
processWord(xBuf, 0);
xBufOff = 0;
}
byteCount++;
}
public void update(
byte[] in,
int inOff,
int len)
{
//
// fill the current word
//
while ((xBufOff != 0) && (len > 0))
{
update(in[inOff]);
inOff++;
len--;
}
//
// process whole words.
//
while (len > xBuf.length)
{
processWord(in, inOff);
inOff += xBuf.length;
len -= xBuf.length;
byteCount += xBuf.length;
}
//
// load in the remainder.
//
while (len > 0)
{
update(in[inOff]);
inOff++;
len--;
}
}
public void finish()
{
long bitLength = (byteCount << 3);
//
// add the pad bytes.
//
update((byte)128);
while (xBufOff != 0)
{
update((byte)0);
}
processLength(bitLength);
processBlock();
}
public void reset()
{
byteCount = 0;
xBufOff = 0;
for (int i = 0; i < xBuf.length; i++)
{
xBuf[i] = 0;
}
}
protected void populateState(byte[] state)
{
System.arraycopy(xBuf, 0, state, 0, xBufOff);
Pack.intToBigEndian(xBufOff, state, 4);
Pack.longToBigEndian(byteCount, state, 8);
}
public int getByteLength()
{
return BYTE_LENGTH;
}
protected abstract void processWord(byte[] in, int inOff);
protected abstract void processLength(long bitLength);
protected abstract void processBlock();
}
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