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package org.bouncycastle.crypto.digests;
import org.bouncycastle.crypto.ExtendedDigest;
import org.bouncycastle.crypto.engines.ThreefishEngine;
import org.bouncycastle.crypto.params.SkeinParameters;
import org.bouncycastle.util.Memoable;
/**
* Implementation of the Skein parameterised hash function in 256, 512 and 1024 bit block sizes,
* based on the {@link ThreefishEngine Threefish} tweakable block cipher.
* <p>
* This is the 1.3 version of Skein defined in the Skein hash function submission to the NIST SHA-3
* competition in October 2010.
* <p>
* Skein was designed by Niels Ferguson - Stefan Lucks - Bruce Schneier - Doug Whiting - Mihir
* Bellare - Tadayoshi Kohno - Jon Callas - Jesse Walker.
*
* @see SkeinEngine
* @see SkeinParameters
*/
public class SkeinDigest
implements ExtendedDigest, Memoable
{
/**
* 256 bit block size - Skein-256
*/
public static final int SKEIN_256 = SkeinEngine.SKEIN_256;
/**
* 512 bit block size - Skein-512
*/
public static final int SKEIN_512 = SkeinEngine.SKEIN_512;
/**
* 1024 bit block size - Skein-1024
*/
public static final int SKEIN_1024 = SkeinEngine.SKEIN_1024;
private SkeinEngine engine;
/**
* Constructs a Skein digest with an internal state size and output size.
*
* @param stateSizeBits the internal state size in bits - one of {@link #SKEIN_256}, {@link #SKEIN_512} or
* {@link #SKEIN_1024}.
* @param digestSizeBits the output/digest size to produce in bits, which must be an integral number of
* bytes.
*/
public SkeinDigest(int stateSizeBits, int digestSizeBits)
{
this.engine = new SkeinEngine(stateSizeBits, digestSizeBits);
init(null);
}
public SkeinDigest(SkeinDigest digest)
{
this.engine = new SkeinEngine(digest.engine);
}
public void reset(Memoable other)
{
SkeinDigest d = (SkeinDigest)other;
engine.reset(d.engine);
}
public Memoable copy()
{
return new SkeinDigest(this);
}
public String getAlgorithmName()
{
return "Skein-" + (engine.getBlockSize() * 8) + "-" + (engine.getOutputSize() * 8);
}
public int getDigestSize()
{
return engine.getOutputSize();
}
public int getByteLength()
{
return engine.getBlockSize();
}
/**
* Optionally initialises the Skein digest with the provided parameters.<br>
* See {@link SkeinParameters} for details on the parameterisation of the Skein hash function.
*
* @param params the parameters to apply to this engine, or <code>null</code> to use no parameters.
*/
public void init(SkeinParameters params)
{
engine.init(params);
}
public void reset()
{
engine.reset();
}
public void update(byte in)
{
engine.update(in);
}
public void update(byte[] in, int inOff, int len)
{
engine.update(in, inOff, len);
}
public int doFinal(byte[] out, int outOff)
{
return engine.doFinal(out, outOff);
}
}
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