public class

CFBBlockCipher

extends Object
implements BlockCipher
java.lang.Object
   ↳ org.bouncycastle.crypto.modes.CFBBlockCipher

Class Overview

implements a Cipher-FeedBack (CFB) mode on top of a simple cipher.

Summary

Public Constructors
CFBBlockCipher(BlockCipher cipher, int bitBlockSize)
Basic constructor.
Public Methods
int decryptBlock(byte[] in, int inOff, byte[] out, int outOff)
Do the appropriate processing for CFB mode decryption.
int encryptBlock(byte[] in, int inOff, byte[] out, int outOff)
Do the appropriate processing for CFB mode encryption.
String getAlgorithmName()
return the algorithm name and mode.
int getBlockSize()
return the block size we are operating at.
BlockCipher getUnderlyingCipher()
return the underlying block cipher that we are wrapping.
void init(boolean encrypting, CipherParameters params)
Initialise the cipher and, possibly, the initialisation vector (IV).
int processBlock(byte[] in, int inOff, byte[] out, int outOff)
Process one block of input from the array in and write it to the out array.
void reset()
reset the chaining vector back to the IV and reset the underlying cipher.
[Expand]
Inherited Methods
From class java.lang.Object
From interface org.bouncycastle.crypto.BlockCipher

Public Constructors

public CFBBlockCipher (BlockCipher cipher, int bitBlockSize)

Basic constructor.

Parameters
cipher the block cipher to be used as the basis of the feedback mode.
bitBlockSize the block size in bits (note: a multiple of 8)

Public Methods

public int decryptBlock (byte[] in, int inOff, byte[] out, int outOff)

Do the appropriate processing for CFB mode decryption.

Parameters
in the array containing the data to be decrypted.
inOff offset into the in array the data starts at.
out the array the encrypted data will be copied into.
outOff the offset into the out array the output will start at.
Returns
  • the number of bytes processed and produced.
Throws
DataLengthException if there isn't enough data in in, or space in out.
IllegalStateException if the cipher isn't initialised.

public int encryptBlock (byte[] in, int inOff, byte[] out, int outOff)

Do the appropriate processing for CFB mode encryption.

Parameters
in the array containing the data to be encrypted.
inOff offset into the in array the data starts at.
out the array the encrypted data will be copied into.
outOff the offset into the out array the output will start at.
Returns
  • the number of bytes processed and produced.
Throws
DataLengthException if there isn't enough data in in, or space in out.
IllegalStateException if the cipher isn't initialised.

public String getAlgorithmName ()

return the algorithm name and mode.

Returns
  • the name of the underlying algorithm followed by "/CFB" and the block size in bits.

public int getBlockSize ()

return the block size we are operating at.

Returns
  • the block size we are operating at (in bytes).

public BlockCipher getUnderlyingCipher ()

return the underlying block cipher that we are wrapping.

Returns
  • the underlying block cipher that we are wrapping.

public void init (boolean encrypting, CipherParameters params)

Initialise the cipher and, possibly, the initialisation vector (IV). If an IV isn't passed as part of the parameter, the IV will be all zeros. An IV which is too short is handled in FIPS compliant fashion.

Parameters
encrypting if true the cipher is initialised for encryption, if false for decryption.
params the key and other data required by the cipher.
Throws
IllegalArgumentException if the params argument is inappropriate.

public int processBlock (byte[] in, int inOff, byte[] out, int outOff)

Process one block of input from the array in and write it to the out array.

Parameters
in the array containing the input data.
inOff offset into the in array the data starts at.
out the array the output data will be copied into.
outOff the offset into the out array the output will start at.
Returns
  • the number of bytes processed and produced.
Throws
DataLengthException if there isn't enough data in in, or space in out.
IllegalStateException if the cipher isn't initialised.

public void reset ()

reset the chaining vector back to the IV and reset the underlying cipher.