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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 1.4.
package org.bouncycastle.crypto.modes;
import org.bouncycastle.crypto.BlockCipher;
import org.bouncycastle.crypto.BufferedBlockCipher;
import org.bouncycastle.crypto.DataLengthException;
import org.bouncycastle.crypto.InvalidCipherTextException;
/**
* A wrapper class that allows block ciphers to be used to process data in
* a piecemeal fashion with PKCS5/PKCS7 padding. The PaddedBlockCipher
* outputs a block only when the buffer is full and more data is being added,
* or on a doFinal (unless the current block in the buffer is a pad block).
* The padding mechanism used is the one outlined in PKCS5/PKCS7.
*
* @deprecated use org.bouncycastle.crypto.paddings.PaddedBufferedBlockCipher instead.
*/
public class PaddedBlockCipher
extends BufferedBlockCipher
{
/**
* Create a buffered block cipher with, or without, padding.
*
* @param cipher the underlying block cipher this buffering object wraps.
*/
public PaddedBlockCipher(
BlockCipher cipher)
{
this.cipher = cipher;
buf = new byte[cipher.getBlockSize()];
bufOff = 0;
}
/**
* return the size of the output buffer required for an update plus a
* doFinal with an input of len bytes.
*
* @param len the length of the input.
* @return the space required to accommodate a call to update and doFinal
* with len bytes of input.
*/
public int getOutputSize(
int len)
{
int total = len + bufOff;
int leftOver = total % buf.length;
if (leftOver == 0)
{
if (forEncryption)
{
return total + buf.length;
}
return total;
}
return total - leftOver + buf.length;
}
/**
* return the size of the output buffer required for an update
* an input of len bytes.
*
* @param len the length of the input.
* @return the space required to accommodate a call to update
* with len bytes of input.
*/
public int getUpdateOutputSize(
int len)
{
int total = len + bufOff;
int leftOver = total % buf.length;
if (leftOver == 0)
{
return total - buf.length;
}
return total - leftOver;
}
/**
* process a single byte, producing an output block if neccessary.
*
* @param in the input byte.
* @param out the space for any output that might be produced.
* @param outOff the offset from which the output will be copied.
* @exception DataLengthException if there isn't enough space in out.
* @exception IllegalStateException if the cipher isn't initialised.
*/
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);
bufOff = 0;
}
buf[bufOff++] = in;
return resultLen;
}
/**
* process an array of bytes, producing output if necessary.
*
* @param in the input byte array.
* @param inOff the offset at which the input data starts.
* @param len the number of bytes to be copied out of the input array.
* @param out the space for any output that might be produced.
* @param outOff the offset from which the output will be copied.
* @exception DataLengthException if there isn't enough space in out.
* @exception IllegalStateException if the cipher isn't initialised.
*/
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)
{
if ((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);
bufOff = 0;
len -= gapLen;
inOff += gapLen;
while (len > buf.length)
{
resultLen += cipher.processBlock(in, inOff, out, outOff + resultLen);
len -= blockSize;
inOff += blockSize;
}
}
System.arraycopy(in, inOff, buf, bufOff, len);
bufOff += len;
return resultLen;
}
/**
* Process the last block in the buffer. If the buffer is currently
* full and padding needs to be added a call to doFinal will produce
* 2 * getBlockSize() bytes.
*
* @param out the array the block currently being held is copied into.
* @param outOff the offset at which the copying starts.
* @exception DataLengthException if there is insufficient space in out for
* the output or we are decrypting and the input is not block size aligned.
* @exception IllegalStateException if the underlying cipher is not
* initialised.
* @exception InvalidCipherTextException if padding is expected and not found.
*/
public int doFinal(
byte[] out,
int outOff)
throws DataLengthException, IllegalStateException, InvalidCipherTextException
{
int blockSize = cipher.getBlockSize();
int resultLen = 0;
if (forEncryption)
{
if (bufOff == blockSize)
{
if ((outOff + 2 * blockSize) > out.length)
{
throw new DataLengthException("output buffer too short");
}
resultLen = cipher.processBlock(buf, 0, out, outOff);
bufOff = 0;
}
//
// add PKCS7 padding
//
byte code = (byte)(blockSize - bufOff);
while (bufOff < blockSize)
{
buf[bufOff] = code;
bufOff++;
}
resultLen += cipher.processBlock(buf, 0, out, outOff + resultLen);
}
else
{
if (bufOff == blockSize)
{
resultLen = cipher.processBlock(buf, 0, buf, 0);
bufOff = 0;
}
else
{
throw new DataLengthException("last block incomplete in decryption");
}
//
// remove PKCS7 padding
//
int count = buf[blockSize - 1] & 0xff;
if ((count < 0) || (count > blockSize))
{
throw new InvalidCipherTextException("pad block corrupted");
}
resultLen -= count;
System.arraycopy(buf, 0, out, outOff, resultLen);
}
reset();
return resultLen;
}
}
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