/**
* Basic constructor.
*
* @param cipher the block cipher to be used as the basis of the
* feedback mode.
* @param blockSize the block size in bits (note: a multiple of 8)
*/
public CFBBlockCipher(
BlockCipher cipher,
int bitBlockSize)
{
this.cipher = cipher;
this.blockSize = bitBlockSize / 8;
this.IV = new byte[cipher.getBlockSize()];
this.cfbV = new byte[cipher.getBlockSize()];
this.cfbOutV = new byte[cipher.getBlockSize()];
}
/**
* Create a buffered block cipher without padding.
*
* @param cipher the underlying block cipher this buffering object wraps.
* @param padded true if the buffer should add, or remove, pad bytes,
* false otherwise.
*/
public BufferedBlockCipher(
BlockCipher cipher)
{
this.cipher = cipher;
buf = new byte[cipher.getBlockSize()];
bufOff = 0;
//
// check if we can handle partial blocks on doFinal.
//
String name = cipher.getAlgorithmName();
int idx = name.IndexOf('/') + 1;
pgpCFB = (idx > 0 && name.Substring(idx).StartsWith("PGP"));
if (pgpCFB)
{
partialBlockOkay = true;
}
else
{
partialBlockOkay = (idx > 0 && (name.Substring(idx).StartsWith("CFB") ||
name.Substring(idx).StartsWith("OFB")));
}
}
/**
* Basic constructor.
*
* @param c the block cipher to be used.
*/
public SICBlockCipher(BlockCipher c)
{
this.cipher = c;
this.blockSize = cipher.getBlockSize();
this.IV = new byte[blockSize];
this.counter = new byte[blockSize];
this.counterOut = new byte[blockSize];
}
/**
* Basic constructor.
*
* @param cipher the block cipher to be used as the basis of chaining.
*/
public CBCBlockCipher(
BlockCipher cipher)
{
this.cipher = cipher;
this.blockSize = cipher.getBlockSize();
this.IV = new byte[blockSize];
this.cbcV = new byte[blockSize];
this.cbcNextV = new byte[blockSize];
}
/**
* Create a buffered block cipher with the desired padding.
*
* @param cipher the underlying block cipher this buffering object wraps.
* @param padding the padding type.
*/
public PaddedBufferedBlockCipher(
BlockCipher cipher,
BlockCipherPadding padding)
{
this.cipher = cipher;
this.padding = padding;
buf = new byte[cipher.getBlockSize()];
bufOff = 0;
}
/**
* basic constructor.
*
* @param cipher the block cipher to be wrapped.
* @exception IllegalArgumentException if the cipher has a block size other than
* one.
*/
public StreamBlockCipher(
BlockCipher cipher)
{
if (cipher.getBlockSize() != 1)
{
throw new ArgumentException("block cipher block size != 1.");
}
this.cipher = cipher;
}
/**
* create a standard MAC based on a block cipher with the size of the
* MAC been given in bits. This class uses CBC mode as the basis for the
* MAC generation.
* <p>
* Note: the size of the MAC must be at least 24 bits (FIPS Publication 81),
* or 16 bits if being used as a data authenticator (FIPS Publication 113),
* and in general should be less than the size of the block cipher as it reduces
* the chance of an exhaustive attack (see Handbook of Applied Cryptography).
*
* @param cipher the cipher to be used as the basis of the MAC generation.
* @param macSizeInBits the size of the MAC in bits, must be a multiple of 8.
* @param padding the padding to be used to complete the last block.
*/
public CBCBlockCipherMac(
BlockCipher cipher,
int macSizeInBits,
BlockCipherPadding padding)
{
if ((macSizeInBits % 8) != 0)
{
throw new ArgumentException("MAC size must be multiple of 8");
}
this.cipher = new CBCBlockCipher(cipher);
this.padding = padding;
this.macSize = macSizeInBits / 8;
mac = new byte[cipher.getBlockSize()];
buf = new byte[cipher.getBlockSize()];
bufOff = 0;
}
public void update(
byte[] inBytes,
int inOff,
int len)
{
if (len < 0)
{
throw new ArgumentException("Can't have a negative input length!");
}
int blockSize = cipher.getBlockSize();
int resultLen = 0;
int gapLen = blockSize - bufOff;
if (len > gapLen)
{
Array.Copy(inBytes, inOff, buf, bufOff, gapLen);
resultLen += cipher.processBlock(buf, 0, mac, 0);
bufOff = 0;
len -= gapLen;
inOff += gapLen;
while (len > blockSize)
{
resultLen += cipher.processBlock(inBytes, inOff, mac, 0);
len -= blockSize;
inOff += blockSize;
}
}
Array.Copy(inBytes, inOff, buf, bufOff, len);
bufOff += len;
}
/**
* return the block size of the underlying cipher.
*
* @return the block size of the underlying cipher.
*/
public int getBlockSize()
{
return(cipher.getBlockSize());
}
/**
* create a standard MAC based on a CBC block cipher. This will produce an
* authentication code half the length of the block size of the cipher.
*
* @param cipher the cipher to be used as the basis of the MAC generation.
* @param padding the padding to be used to complete the last block.
*/
public CBCBlockCipherMac(
BlockCipher cipher,
BlockCipherPadding padding)
: this(cipher, (cipher.getBlockSize() * 8) / 2, padding)
{
}
/**
* create a standard MAC based on a CBC block cipher. This will produce an
* authentication code half the length of the block size of the cipher.
*
* @param cipher the cipher to be used as the basis of the MAC generation.
*/
public CBCBlockCipherMac(BlockCipher cipher)
: this(cipher, (cipher.getBlockSize() * 8) / 2, null)
{
}
/**
* return the blocksize for the underlying cipher.
*
* @return the blocksize for the underlying cipher.
*/
public virtual int getBlockSize()
{
return(cipher.getBlockSize());
}