ShakeDigest
Implementation of SHAKE based on following KeccakNISTInterface.c from http://keccak.noekeon.org/
using Org.BouncyCastle.Utilities;
using System;
namespace Org.BouncyCastle.Crypto.Digests
{
public class ShakeDigest : KeccakDigest, IXof, IDigest
{
public override string AlgorithmName => "SHAKE" + fixedOutputLength.ToString();
private static int CheckBitLength(int bitLength)
{
if (bitLength == 128 || bitLength == 256)
return bitLength;
throw new ArgumentException(bitLength.ToString() + " not supported for SHAKE", "bitLength");
}
public ShakeDigest()
: this(128)
{
}
public ShakeDigest(int bitLength)
: base(CheckBitLength(bitLength))
{
}
public ShakeDigest(ShakeDigest source)
: base(source)
{
}
public override int GetDigestSize()
{
return fixedOutputLength >> 2;
}
public override int DoFinal(byte[] output, int outOff)
{
return OutputFinal(output, outOff, GetDigestSize());
}
public virtual int OutputFinal(byte[] output, int outOff, int outLen)
{
int result = Output(output, outOff, outLen);
Reset();
return result;
}
public virtual int Output(byte[] output, int outOff, int outLen)
{
if (!squeezing)
AbsorbBits(15, 4);
Squeeze(output, outOff, (long)outLen << 3);
return outLen;
}
protected override int DoFinal(byte[] output, int outOff, byte partialByte, int partialBits)
{
return OutputFinal(output, outOff, GetDigestSize(), partialByte, partialBits);
}
protected virtual int OutputFinal(byte[] output, int outOff, int outLen, byte partialByte, int partialBits)
{
if (partialBits < 0 || partialBits > 7)
throw new ArgumentException("must be in the range [0,7]", "partialBits");
int num = (partialByte & ((1 << partialBits) - 1)) | (15 << partialBits);
int num2 = partialBits + 4;
if (num2 >= 8) {
Absorb((byte)num);
num2 -= 8;
num >>= 8;
}
if (num2 > 0)
AbsorbBits(num, num2);
Squeeze(output, outOff, (long)outLen << 3);
Reset();
return outLen;
}
public override IMemoable Copy()
{
return new ShakeDigest(this);
}
}
}