com.googlecode.gwt.crypto.bouncycastle.engines.DESedeEngine Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of gwt-crypto Show documentation
A partial port of the Bouncycastle J2ME crypto library with parts taken from GWTx.
The newest version!
package com.googlecode.gwt.crypto.bouncycastle.engines;


import com.googlecode.gwt.crypto.bouncycastle.CipherParameters;
import com.googlecode.gwt.crypto.bouncycastle.DataLengthException;
import com.googlecode.gwt.crypto.bouncycastle.params.KeyParameter;
import com.googlecode.gwt.crypto.util.Sys;


/**
 * a class that provides a basic DESede (or Triple DES) engine.
 */
public class DESedeEngine extends DESEngine {
	protected static final int	BLOCK_SIZE	= 8;

	private int[]				workingKey1	= null;
	private int[]				workingKey2	= null;
	private int[]				workingKey3	= null;

	private boolean				forEncryption;

	/**
	 * standard constructor.
	 */
	public DESedeEngine() {
	}

	/**
	 * initialise a DESede cipher.
	 * 
	 * @param encrypting
	 *            whether or not we are for encryption.
	 * @param params
	 *            the parameters required to set up the cipher.
	 * @exception IllegalArgumentException
	 *                if the params argument is inappropriate.
	 */
	@Override
	public void init(boolean encrypting, CipherParameters params) {
		if (!(params instanceof KeyParameter)) {
			throw new IllegalArgumentException("invalid parameter passed to DESede init - " + params.getClass().getName());
		}

		byte[] keyMaster = ((KeyParameter) params).getKey();
		byte[] key1 = new byte[8], key2 = new byte[8], key3 = new byte[8];

		if (keyMaster.length > 24) {
			throw new IllegalArgumentException("key size greater than 24 bytes");
		}
		if (keyMaster.length < 16) {
			throw new IllegalArgumentException("key size greater than 16 bytes");
		}

		

		this.forEncryption = encrypting;

		if (keyMaster.length == 24) {
			Sys.arraycopy(keyMaster, 0, key1, 0, key1.length);
			Sys.arraycopy(keyMaster, 8, key2, 0, key2.length);
			Sys.arraycopy(keyMaster, 16, key3, 0, key3.length);

			workingKey1 = generateWorkingKey(encrypting, key1);
			workingKey2 = generateWorkingKey(!encrypting, key2);
			workingKey3 = generateWorkingKey(encrypting, key3);
		} else // 16 byte key
		{
			Sys.arraycopy(keyMaster, 0, key1, 0, key1.length);
			Sys.arraycopy(keyMaster, 8, key2, 0, key2.length);

			workingKey1 = generateWorkingKey(encrypting, key1);
			workingKey2 = generateWorkingKey(!encrypting, key2);
			workingKey3 = workingKey1;
		}
	}

	@Override
	public String getAlgorithmName() {
		return "DESede";
	}

	@Override
	public int getBlockSize() {
		return BLOCK_SIZE;
	}

	@Override
	public int processBlock(byte[] in, int inOff, byte[] out, int outOff) {
		if (workingKey1 == null) {
			throw new IllegalStateException("DESede engine not initialised");
		}

		if ((inOff + BLOCK_SIZE) > in.length) {
			throw new DataLengthException("input buffer too short");
		}

		if ((outOff + BLOCK_SIZE) > out.length) {
			throw new DataLengthException("output buffer too short");
		}

		if (forEncryption) {
			desFunc(workingKey1, in, inOff, out, outOff);
			desFunc(workingKey2, out, outOff, out, outOff);
			desFunc(workingKey3, out, outOff, out, outOff);
		} else {
			desFunc(workingKey3, in, inOff, out, outOff);
			desFunc(workingKey2, out, outOff, out, outOff);
			desFunc(workingKey1, out, outOff, out, outOff);
		}

		return BLOCK_SIZE;
	}

	@Override
	public void reset() {
	}
}