ctsblockcipher.java

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// Decompiled by Jad v1.5.8e2. Copyright 2001 Pavel Kouznetsov.
// Jad home page: http://kpdus.tripod.com/jad.html
// Decompiler options: packimports(3) fieldsfirst ansi space 
// Source File Name:   CTSBlockCipher.java

package org.bouncycastle.crypto.modes;

import org.bouncycastle.crypto.*;

// Referenced classes of package org.bouncycastle.crypto.modes:
//			CBCBlockCipher, CFBBlockCipher, OFBBlockCipher

public class CTSBlockCipher extends BufferedBlockCipher
{

	private int blockSize;

	public CTSBlockCipher(BlockCipher cipher)
	{
		if ((cipher instanceof OFBBlockCipher) || (cipher instanceof CFBBlockCipher))
		{
			throw new IllegalArgumentException("CTSBlockCipher can only accept ECB, or CBC ciphers");
		} else
		{
			this.cipher = cipher;
			blockSize = cipher.getBlockSize();
			buf = new byte[blockSize * 2];
			bufOff = 0;
			return;
		}
	}

	public int getUpdateOutputSize(int len)
	{
		int total = len + bufOff;
		int leftOver = total % buf.length;
		if (leftOver == 0)
			return total - buf.length;
		else
			return total - leftOver;
	}

	public int getOutputSize(int len)
	{
		return len + bufOff;
	}

	public int processByte(byte in, byte out[], int outOff)
		throws DataLengthException, IllegalStateException
	{
		int resultLen = 0;
		if (bufOff == buf.length)
		{
			resultLen = cipher.processBlock(buf, 0, out, outOff);
			System.arraycopy(buf, blockSize, buf, 0, blockSize);
			bufOff = blockSize;
		}
		buf[bufOff++] = in;
		return resultLen;
	}

	public int processBytes(byte in[], int inOff, int len, byte out[], int outOff)
		throws DataLengthException, IllegalStateException
	{
		if (len < 0)
			throw new IllegalArgumentException("Can't have a negative input length!");
		int blockSize = getBlockSize();
		int length = getUpdateOutputSize(len);
		if (length > 0 && outOff + length > out.length)
			throw new DataLengthException("output buffer too short");
		int resultLen = 0;
		int gapLen = buf.length - bufOff;
		if (len > gapLen)
		{
			System.arraycopy(in, inOff, buf, bufOff, gapLen);
			resultLen += cipher.processBlock(buf, 0, out, outOff);
			System.arraycopy(buf, blockSize, buf, 0, blockSize);
			bufOff = blockSize;
			len -= gapLen;
			for (inOff += gapLen; len > blockSize; inOff += blockSize)
			{
				System.arraycopy(in, inOff, buf, bufOff, blockSize);
				resultLen += cipher.processBlock(buf, 0, out, outOff + resultLen);
				System.arraycopy(buf, blockSize, buf, 0, blockSize);
				len -= blockSize;
			}

		}
		System.arraycopy(in, inOff, buf, bufOff, len);
		bufOff += len;
		return resultLen;
	}

	public int doFinal(byte out[], int outOff)
		throws DataLengthException, IllegalStateException, InvalidCipherTextException
	{
		if (bufOff + outOff > out.length)
			throw new DataLengthException("output buffer to small in doFinal");
		int blockSize = cipher.getBlockSize();
		int len = bufOff - blockSize;
		byte block[] = new byte[blockSize];
		if (forEncryption)
		{
			cipher.processBlock(buf, 0, block, 0);
			for (int i = bufOff; i != buf.length; i++)
				buf[i] = block[i - blockSize];

			for (int i = blockSize; i != bufOff; i++)
				buf[i] ^= block[i - blockSize];

			if (cipher instanceof CBCBlockCipher)
			{
				BlockCipher c = ((CBCBlockCipher)cipher).getUnderlyingCipher();
				c.processBlock(buf, blockSize, out, outOff);
			} else
			{
				cipher.processBlock(buf, blockSize, out, outOff);
			}
			System.arraycopy(block, 0, out, outOff + blockSize, len);
		} else
		{
			byte lastBlock[] = new byte[blockSize];
			if (cipher instanceof CBCBlockCipher)
			{
				BlockCipher c = ((CBCBlockCipher)cipher).getUnderlyingCipher();
				c.processBlock(buf, 0, block, 0);
			} else
			{
				cipher.processBlock(buf, 0, block, 0);
			}
			for (int i = blockSize; i != bufOff; i++)
				lastBlock[i - blockSize] = (byte)(block[i - blockSize] ^ buf[i]);

			System.arraycopy(buf, blockSize, block, 0, len);
			cipher.processBlock(block, 0, out, outOff);
			System.arraycopy(lastBlock, 0, out, outOff + blockSize, len);
		}
		int offset = bufOff;
		reset();
		return offset;
	}
}