de.flexiprovider.common.mode
Class CFB

java.lang.Object
  |
  +--de.flexiprovider.api.Mode
        |
        +--de.flexiprovider.common.mode.CFB

public class CFB

extends Mode

Cipher feedback mode for symmetric block ciphers.

This class currently only supports 1-byte feedback which should be sufficient for most applications. For further information, see "Handbook of Applied Cryptography", Note 7.17. WARNING: CFB feedback should be in BYTES. The default value is 1 Byte(8 Bits)

Author:

Ralf-P. Weinmann

Fields inherited from class de.flexiprovider.api.Mode

blockSize, iv

Constructor Summary

CFB()

Method Summary

protected void	initDecrypt(SecretKey key, ModeParameterSpec modeParams, AlgorithmParameterSpec paramSpec) Initialize the Mode object for decryption.
protected void	initEncrypt(SecretKey key, ModeParameterSpec modeParams, AlgorithmParameterSpec cipherParams) Initialize the Mode object for encryption.
protected void	nextChunkDecrypt(byte[] input, int inOff, byte[] output, int outOff) Decrypt the next data block.
protected void	nextChunkEncrypt(byte[] input, int inOff, byte[] output, int outOff) Encrypt the next data block.
protected void	reset() Reset shift block to initialization vector.

Methods inherited from class de.flexiprovider.api.Mode

getCipherBlockSize, initCipherDecrypt, initCipherEncrypt, setBlockCipher, singleBlockDecrypt, singleBlockEncrypt

Methods inherited from class java.lang.Object

, clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

CFB

public CFB()

Method Detail

initEncrypt

protected final void initEncrypt(SecretKey key,
                                 ModeParameterSpec modeParams,
                                 AlgorithmParameterSpec cipherParams)
                          throws InvalidKeyException,
                                 InvalidAlgorithmParameterException

Initialize the Mode object for encryption.

Overrides:

initEncrypt in class Mode

Parameters:

key - the key used for encryption

modeParams - additional mode parameters

cipherParams - additional algorithm parameters

Throws:

InvalidKeyException - if the key is inappropriate for initializing the underlying block cipher.

InvalidAlgorithmParameterException - if the parameters are inappropriate for initializing the underlying block cipher.

initDecrypt

protected final void initDecrypt(SecretKey key,
                                 ModeParameterSpec modeParams,
                                 AlgorithmParameterSpec paramSpec)
                          throws InvalidKeyException,
                                 InvalidAlgorithmParameterException

Initialize the Mode object for decryption.

Overrides:

initDecrypt in class Mode

Parameters:

key - the key used for decryption

modeParams - additional mode parameters

paramSpec - additional algorithm parameters

Throws:

InvalidKeyException - if the key is inappropriate for initializing the underlying block cipher.

InvalidAlgorithmParameterException - if the parameters are inappropriate for initializing the underlying block cipher.

nextChunkEncrypt

protected final void nextChunkEncrypt(byte[] input,
                                      int inOff,
                                      byte[] output,
                                      int outOff)

Encrypt the next data block. Any special features of the Mode should be implemented here.

Overrides:

nextChunkEncrypt in class Mode

Parameters:

input - input data buffer

inOff - input data offset

output - output data buffer

outOff - output data offset

nextChunkDecrypt

protected final void nextChunkDecrypt(byte[] input,
                                      int inOff,
                                      byte[] output,
                                      int outOff)

Decrypt the next data block. Any special features of the Mode should be implemented here.

Overrides:

nextChunkDecrypt in class Mode

Parameters:

input - input data buffer

inOff - input data offset

output - output data buffer

outOff - output data offset

reset

protected final void reset()

Reset shift block to initialization vector.

Overrides:

reset in class Mode