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package org.spongycastle.crypto.macs;
import org.spongycastle.crypto.CipherParameters;
import org.spongycastle.crypto.Mac;
import org.spongycastle.crypto.digests.SkeinEngine;
import org.spongycastle.crypto.engines.ThreefishEngine;
import org.spongycastle.crypto.params.KeyParameter;
import org.spongycastle.crypto.params.SkeinParameters;
/**
* Implementation of the Skein parameterised MAC 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 SkeinMac
implements Mac
{
/**
* 256 bit block size - Skein MAC-256
*/
public static final int SKEIN_256 = SkeinEngine.SKEIN_256;
/**
* 512 bit block size - Skein MAC-512
*/
public static final int SKEIN_512 = SkeinEngine.SKEIN_512;
/**
* 1024 bit block size - Skein MAC-1024
*/
public static final int SKEIN_1024 = SkeinEngine.SKEIN_1024;
private SkeinEngine engine;
/**
* Constructs a Skein MAC 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/MAC size to produce in bits, which must be an integral number of bytes.
*/
public SkeinMac(int stateSizeBits, int digestSizeBits)
{
this.engine = new SkeinEngine(stateSizeBits, digestSizeBits);
}
public SkeinMac(SkeinMac mac)
{
this.engine = new SkeinEngine(mac.engine);
}
public String getAlgorithmName()
{
return "Skein-MAC-" + (engine.getBlockSize() * 8) + "-" + (engine.getOutputSize() * 8);
}
/**
* Initialises the Skein digest with the provided parameters.<br>
* See {@link SkeinParameters} for details on the parameterisation of the Skein hash function.
*
* @param params an instance of {@link SkeinParameters} or {@link KeyParameter}.
*/
public void init(CipherParameters params)
throws IllegalArgumentException
{
SkeinParameters skeinParameters;
if (params instanceof SkeinParameters)
{
skeinParameters = (SkeinParameters)params;
}
else if (params instanceof KeyParameter)
{
skeinParameters = new SkeinParameters.Builder().setKey(((KeyParameter)params).getKey()).build();
}
else
{
throw new IllegalArgumentException("Invalid parameter passed to Skein MAC init - "
+ params.getClass().getName());
}
if (skeinParameters.getKey() == null)
{
throw new IllegalArgumentException("Skein MAC requires a key parameter.");
}
engine.init(skeinParameters);
}
public int getMacSize()
{
return engine.getOutputSize();
}
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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