org.bouncycastle.crypto.digests.SHAKEDigest Maven / Gradle / Ivy
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package org.bouncycastle.crypto.digests;
import org.bouncycastle.crypto.Xof;
/**
* implementation of SHAKE based on following KeccakNISTInterface.c from http://keccak.noekeon.org/
*
* Following the naming conventions used in the C source code to enable easy review of the implementation.
*/
public class SHAKEDigest
extends KeccakDigest
implements Xof
{
private static int checkBitLength(int bitLength)
{
switch (bitLength)
{
case 128:
case 256:
return bitLength;
default:
throw new IllegalArgumentException("'bitLength' " + bitLength + " not supported for SHAKE");
}
}
public SHAKEDigest()
{
this(128);
}
public SHAKEDigest(int bitLength)
{
super(checkBitLength(bitLength));
}
public SHAKEDigest(SHAKEDigest source) {
super(source);
}
public String getAlgorithmName()
{
return "SHAKE" + fixedOutputLength;
}
public int doFinal(byte[] out, int outOff)
{
return doFinal(out, outOff, getDigestSize());
}
public int doFinal(byte[] out, int outOff, int outLen)
{
int length = doOutput(out, outOff, outLen);
reset();
return length;
}
public int doOutput(byte[] out, int outOff, int outLen)
{
if (!squeezing)
{
absorbBits(0x0F, 4);
}
squeeze(out, outOff, ((long)outLen) * 8);
return outLen;
}
/*
* TODO Possible API change to support partial-byte suffixes.
*/
protected int doFinal(byte[] out, int outOff, byte partialByte, int partialBits)
{
return doFinal(out, outOff, getDigestSize(), partialByte, partialBits);
}
/*
* TODO Possible API change to support partial-byte suffixes.
*/
protected int doFinal(byte[] out, int outOff, int outLen, byte partialByte, int partialBits)
{
if (partialBits < 0 || partialBits > 7)
{
throw new IllegalArgumentException("'partialBits' must be in the range [0,7]");
}
int finalInput = (partialByte & ((1 << partialBits) - 1)) | (0x0F << partialBits);
int finalBits = partialBits + 4;
if (finalBits >= 8)
{
absorb(new byte[]{ (byte)finalInput }, 0, 1);
finalBits -= 8;
finalInput >>>= 8;
}
if (finalBits > 0)
{
absorbBits(finalInput, finalBits);
}
squeeze(out, outOff, ((long)outLen) * 8);
reset();
return outLen;
}
}