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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 and up.
package org.bouncycastle.crypto.macs;
import org.bouncycastle.crypto.CipherParameters;
import org.bouncycastle.crypto.Mac;
import org.bouncycastle.crypto.engines.Zuc256CoreEngine;
/**
* Zuc256 Mac implementation.
* Based on http://www.is.cas.cn/ztzl2016/zouchongzhi/201801/W020180126529970733243.pdf
*/
public final class Zuc256Mac
implements Mac
{
/**
* The Maximum Bit Mask.
*/
private static final int TOPBIT = 0x80;
/**
* The Zuc256 Engine.
*/
private final InternalZuc256Engine theEngine;
/**
* The mac length.
*/
private final int theMacLength;
/**
* The calculated Mac in words.
*/
private final int[] theMac;
/**
* The active keyStream.
*/
private final int[] theKeyStream;
/**
* The initialised state.
*/
private Zuc256CoreEngine theState;
/**
* The current word index.
*/
private int theWordIndex;
/**
* The current byte index.
*/
private int theByteIndex;
/**
* Constructor.
*
* @param pLength the bit length of the Mac
*/
public Zuc256Mac(final int pLength)
{
theEngine = new InternalZuc256Engine(pLength);
theMacLength = pLength;
final int numWords = pLength / 32; // Integer.SIZE
theMac = new int[numWords];
theKeyStream = new int[numWords + 1];
}
/**
* Obtain Algorithm Name.
*
* @return the name
*/
public String getAlgorithmName()
{
return "Zuc256Mac-" + theMacLength;
}
/**
* Obtain Mac Size.
*
* @return the size in Bytes
*/
public int getMacSize()
{
return theMacLength / 8; //Byte.SIZE
}
/**
* Initialise the Mac.
*
* @param pParams the parameters
*/
public void init(final CipherParameters pParams)
{
/* Initialise the engine */
theEngine.init(true, pParams);
theState = (Zuc256CoreEngine)theEngine.copy();
initKeyStream();
}
/**
* Initialise the keyStream.
*/
private void initKeyStream()
{
/* Initialise the Mac */
for (int i = 0; i < theMac.length; i++)
{
theMac[i] = theEngine.createKeyStreamWord();
}
/* Initialise the KeyStream */
for (int i = 0; i < theKeyStream.length - 1; i++)
{
theKeyStream[i] = theEngine.createKeyStreamWord();
}
theWordIndex = theKeyStream.length - 1;
theByteIndex = 4 - 1; // Integer.SIZE
}
/**
* Update the mac with a single byte.
*
* @param in the byte to update with
*/
public void update(final byte in)
{
/* shift for next byte */
shift4NextByte();
/* Loop through the bits */
final int bitBase = theByteIndex * 8; //Byte.SIZE;
for (int bitMask = TOPBIT, bitNo = 0; bitMask > 0; bitMask >>= 1, bitNo++)
{
/* If the bit is set */
if ((in & bitMask) != 0)
{
/* update theMac */
updateMac(bitBase + bitNo);
}
}
}
/**
* Shift for next byte.
*/
private void shift4NextByte()
{
/* Adjust the byte index */
theByteIndex = (theByteIndex + 1) % 4; //Integer.BYTES
/* Adjust keyStream if required */
if (theByteIndex == 0)
{
theKeyStream[theWordIndex] = theEngine.createKeyStreamWord();
theWordIndex = (theWordIndex + 1) % theKeyStream.length;
}
}
/**
* Shift for final update.
*/
private void shift4Final()
{
/* Adjust the byte index */
theByteIndex = (theByteIndex + 1) % 4; //Integer.BYTES
/* No need to read another word to the keyStream */
if (theByteIndex == 0)
{
theWordIndex = (theWordIndex + 1) % theKeyStream.length;
}
}
/**
* Update the Mac.
*
* @param bitNo the bit number
*/
private void updateMac(final int bitNo)
{
/* Loop through the Mac */
for (int wordNo = 0; wordNo < theMac.length; wordNo++)
{
theMac[wordNo] ^= getKeyStreamWord(wordNo, bitNo);
}
}
/**
* Obtain the keyStreamWord.
*
* @param wordNo the wordNumber
* @param bitNo the bitNumber
* @return the word
*/
private int getKeyStreamWord(final int wordNo, final int bitNo)
{
/* Access the first word and return it if this is bit 0 */
final int myFirst = theKeyStream[(theWordIndex + wordNo) % theKeyStream.length];
if (bitNo == 0)
{
return myFirst;
}
/* Access the second word */
final int mySecond = theKeyStream[(theWordIndex + wordNo + 1) % theKeyStream.length];
return (myFirst << bitNo) | (mySecond >>> (32 - bitNo)); //Integer.SIZE - bitNo
}
/**
* Update the mac.
*
* @param in the input buffer
* @param inOff the starting offset in the input buffer
* @param len the length of data to process
*/
public void update(final byte[] in, final int inOff, final int len)
{
for (int byteNo = 0; byteNo < len; byteNo++)
{
update(in[inOff + byteNo]);
}
}
/**
* Finalize the mac.
*
* @param out the output buffer
* @param outOff the starting offset in the output buffer
* @return the size of the mac
*/
public int doFinal(final byte[] out, final int outOff)
{
/* shift for final update */
shift4Final();
/* Finish the Mac and output it */
updateMac(theByteIndex * 8); //Byte.SIZE)
for (int i = 0; i < theMac.length; i++)
{
Zuc256CoreEngine.encode32be(theMac[i], out, outOff + i * 4); //Integer.BYTES)
}
/* Reset the Mac */
reset();
return getMacSize();
}
/**
* Reset the Mac.
*/
public void reset()
{
if (theState != null)
{
theEngine.reset(theState);
}
initKeyStream();
}
private static class InternalZuc256Engine
extends Zuc256CoreEngine
{
public InternalZuc256Engine(int pLength)
{
super(pLength);
}
int createKeyStreamWord()
{
return super.makeKeyStreamWord();
}
}
}