using System;
using System.Diagnostics;
using Org.BouncyCastle.Crypto.Parameters;
namespace Org.BouncyCastle.Crypto{
/**
* A wrapper class that allows block ciphers to be used to process data in
* a piecemeal fashion. The BufferedBlockCipher outputs a block only when the
* buffer is full and more data is being added, or on a doFinal.
* <p>
* Note: in the case where the underlying cipher is either a CFB cipher or an
* OFB one the last block may not be a multiple of the block size.
* </p>
*/
public class BufferedBlockCipher
: BufferedCipherBase
{
internal byte[] buf;
internal int bufOff;
internal bool forEncryption;
internal IBlockCipher cipher;
/**
* constructor for subclasses
*/
protected BufferedBlockCipher()
{
}
/**
* Create a buffered block cipher without padding.
*
* @param cipher the underlying block cipher this buffering object wraps.
* false otherwise.
*/
public BufferedBlockCipher(
IBlockCipher cipher)
{
if (cipher == null)
throw new ArgumentNullException("cipher");
this.cipher = cipher;
buf = new byte[cipher.GetBlockSize()];
bufOff = 0;
}
public override string AlgorithmName
{
get { return cipher.AlgorithmName; }
}
/**
* initialise the cipher.
*
* @param forEncryption if true the cipher is initialised for
* encryption, if false for decryption.
* @param param the key and other data required by the cipher.
* @exception ArgumentException if the parameters argument is
* inappropriate.
*/
// Note: This doubles as the Init in the event that this cipher is being used as an IWrapper
public override void Init(
bool forEncryption,
ICipherParameters parameters)
{
this.forEncryption = forEncryption;
if (parameters is ParametersWithRandom)
{
parameters = ((ParametersWithRandom) parameters).Parameters;
}
Reset();
cipher.Init(forEncryption, parameters);
}
/**
* return the blocksize for the underlying cipher.
*
* @return the blocksize for the underlying cipher.
*/
public override int GetBlockSize()
{
return cipher.GetBlockSize();
}
/**
* 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 override int GetUpdateOutputSize(
int length)
{
int total = length + bufOff;
int leftOver = total % buf.Length;
return total - leftOver;
}
/**
* 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 override int GetOutputSize(
int length)
{
// Note: Can assume IsPartialBlockOkay is true for purposes of this calculation
return length + bufOff;
}
/**
* 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.
* @return the number of output bytes copied to out.
* @exception DataLengthException if there isn't enough space in out.
* @exception InvalidOperationException if the cipher isn't initialised.
*/
public override int ProcessByte(
byte input,
byte[] output,
int outOff)
{
buf[bufOff++] = input;
if (bufOff == buf.Length)
{
if ((outOff + buf.Length) > output.Length)
throw new DataLengthException("output buffer too short");
bufOff = 0;
return cipher.ProcessBlock(buf, 0, output, outOff);
}
return 0;
}
public override byte[] ProcessByte(
byte input)
{
int outLength = GetUpdateOutputSize(1);
byte[] outBytes = outLength > 0 ? new byte[outLength] : null;
int pos = ProcessByte(input, outBytes, 0);
if (outLength > 0 && pos < outLength)
{
byte[] tmp = new byte[pos];
Array.Copy(outBytes, 0, tmp, 0, pos);
outBytes = tmp;
}
return outBytes;
}
public override byte[] ProcessBytes(
byte[] input,
int inOff,
int length)
{
if (input == null)
throw new ArgumentNullException("input");
if (length < 1)
return null;
int outLength = GetUpdateOutputSize(length);
byte[] outBytes = outLength > 0 ? new byte[outLength] : null;
int pos = ProcessBytes(input, inOff, length, outBytes, 0);
if (outLength > 0 && pos < outLength)
{
byte[] tmp = new byte[pos];
Array.Copy(outBytes, 0, tmp, 0, pos);
outBytes = tmp;
}
return outBytes;
}
/**
* 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.
* @return the number of output bytes copied to out.
* @exception DataLengthException if there isn't enough space in out.
* @exception InvalidOperationException if the cipher isn't initialised.
*/
public override int ProcessBytes(
byte[] input,
int inOff,
int length,
byte[] output,
int outOff)
{
if (length < 1)
{
if (length < 0)
throw new ArgumentException("Can't have a negative input length!");
return 0;
}
int blockSize = GetBlockSize();
int outLength = GetUpdateOutputSize(length);
if (outLength > 0)
{
if ((outOff + outLength) > output.Length)
{
throw new DataLengthException("output buffer too short");
}
}
int resultLen = 0;
int gapLen = buf.Length - bufOff;
if (length > gapLen)
{
Array.Copy(input, inOff, buf, bufOff, gapLen);
resultLen += cipher.ProcessBlock(buf, 0, output, outOff);
bufOff = 0;
length -= gapLen;
inOff += gapLen;
while (length > buf.Length)
{
resultLen += cipher.ProcessBlock(input, inOff, output, outOff + resultLen);
length -= blockSize;
inOff += blockSize;
}
}
Array.Copy(input, inOff, buf, bufOff, length);
bufOff += length;
if (bufOff == buf.Length)
{
resultLen += cipher.ProcessBlock(buf, 0, output, outOff + resultLen);
bufOff = 0;
}
return resultLen;
}
public override byte[] DoFinal()
{
byte[] outBytes = EmptyBuffer;
int length = GetOutputSize(0);
if (length > 0)
{
outBytes = new byte[length];
int pos = DoFinal(outBytes, 0);
if (pos < outBytes.Length)
{
byte[] tmp = new byte[pos];
Array.Copy(outBytes, 0, tmp, 0, pos);
outBytes = tmp;
}
}
else
{
Reset();
}
return outBytes;
}
public override byte[] DoFinal(
byte[] input,
int inOff,
int inLen)
{
if (input == null)
throw new ArgumentNullException("input");
int length = GetOutputSize(inLen);
byte[] outBytes = EmptyBuffer;
if (length > 0)
{
outBytes = new byte[length];
int pos = (inLen > 0)
? ProcessBytes(input, inOff, inLen, outBytes, 0)
: 0;
pos += DoFinal(outBytes, pos);
if (pos < outBytes.Length)
{
byte[] tmp = new byte[pos];
Array.Copy(outBytes, 0, tmp, 0, pos);
outBytes = tmp;
}
}
else
{
Reset();
}
return outBytes;
}
/**
* Process the last block in the buffer.
*
* @param out the array the block currently being held is copied into.
* @param outOff the offset at which the copying starts.
* @return the number of output bytes copied to out.
* @exception DataLengthException if there is insufficient space in out for
* the output, or the input is not block size aligned and should be.
* @exception InvalidOperationException if the underlying cipher is not
* initialised.
* @exception InvalidCipherTextException if padding is expected and not found.
* @exception DataLengthException if the input is not block size
* aligned.
*/
public override int DoFinal(
byte[] output,
int outOff)
{
if (bufOff != 0)
{
if (!cipher.IsPartialBlockOkay)
{
throw new DataLengthException("data not block size aligned");
}
if (outOff + bufOff > output.Length)
{
throw new DataLengthException("output buffer too short for DoFinal()");
}
// NB: Can't copy directly, or we may write too much output
cipher.ProcessBlock(buf, 0, buf, 0);
Array.Copy(buf, 0, output, outOff, bufOff);
}
int resultLen = bufOff;
Reset();
return resultLen;
}
/**
* Reset the buffer and cipher. After resetting the object is in the same
* state as it was after the last init (if there was one).
*/
public override void Reset()
{
Array.Clear(buf, 0, buf.Length);
bufOff = 0;
cipher.Reset();
}
}
}
|