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The Bouncy Castle Crypto package is a Java implementation of cryptographic algorithms. This jar contains JCE provider and lightweight API for the Bouncy Castle Cryptography APIs for JDK 1.5 to JDK 1.8 with debug enabled.
package org.bouncycastle.crypto.modes;
import org.bouncycastle.crypto.BlockCipher;
import org.bouncycastle.crypto.CipherParameters;
import org.bouncycastle.crypto.DataLengthException;
import org.bouncycastle.crypto.OutputLengthException;
import org.bouncycastle.crypto.StreamBlockCipher;
import org.bouncycastle.crypto.params.ParametersWithIV;
import org.bouncycastle.util.Arrays;
/**
* Implementation of DSTU7624 CTR mode
*/
public class KCTRBlockCipher
extends StreamBlockCipher
{
private byte[] iv;
private byte[] ofbV;
private byte[] ofbOutV;
private int byteCount;
private boolean initialised;
private BlockCipher engine;
public KCTRBlockCipher(BlockCipher engine)
{
super(engine);
this.engine = engine;
this.iv = new byte[engine.getBlockSize()];
this.ofbV = new byte[engine.getBlockSize()];
this.ofbOutV = new byte[engine.getBlockSize()];
}
public void init(boolean forEncryption, CipherParameters params)
throws IllegalArgumentException
{
this.initialised = true;
if (params instanceof ParametersWithIV)
{
ParametersWithIV ivParam = (ParametersWithIV)params;
byte[] iv = ivParam.getIV();
int diff = this.iv.length - iv.length;
Arrays.fill(this.iv, (byte)0);
System.arraycopy(iv, 0, this.iv, diff, iv.length);
params = ivParam.getParameters();
}
else
{
throw new IllegalArgumentException("invalid parameter passed");
}
if (params != null)
{
engine.init(true, params);
}
reset();
}
public String getAlgorithmName()
{
return engine.getAlgorithmName() + "/KCTR";
}
public int getBlockSize()
{
return engine.getBlockSize();
}
protected byte calculateByte(byte b)
{
if (byteCount == 0)
{
incrementCounterAt(0);
checkCounter();
engine.processBlock(ofbV, 0, ofbOutV, 0);
return (byte)(ofbOutV[byteCount++] ^ b);
}
byte rv = (byte)(ofbOutV[byteCount++] ^ b);
if (byteCount == ofbV.length)
{
byteCount = 0;
}
return rv;
}
public int processBlock(byte[] in, int inOff, byte[] out, int outOff)
throws DataLengthException, IllegalStateException
{
if (in.length - inOff < getBlockSize())
{
throw new DataLengthException("input buffer too short");
}
if (out.length - outOff < getBlockSize())
{
throw new OutputLengthException("output buffer too short");
}
processBytes(in, inOff, getBlockSize(), out, outOff);
return getBlockSize();
}
public void reset()
{
if (initialised)
{
engine.processBlock(this.iv, 0, ofbV, 0);
}
engine.reset();
byteCount = 0;
}
private void incrementCounterAt(int pos)
{
int i = pos;
while (i < ofbV.length)
{
if (++ofbV[i++] != 0)
{
break;
}
}
}
private void checkCounter()
{
// TODO:
// if the IV is the same as the blocksize we assume the user knows what they are doing
// if (IV.length < ofbV.length)
// {
// for (int i = 0; i != IV.length; i++)
// {
// if (ofbV[i] != IV[i])
// {
// throw new IllegalStateException("Counter in KCTR mode out of range.");
// }
// }
// }
}
}
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