cryptix.security
Class CipherFeedback

java.lang.Object
  cryptix.security.StreamCipher
      cryptix.security.CipherFeedback

public class CipherFeedback

extends StreamCipher

Implements a byte-based stream cipher using n-bit CFB with an n-bit-sized block cipher.

The full block size of the supplied cipher is used for the Cipher Feedback Mode. The bytes supplied are processed and returned immediately.

Copyright © 1997 Systemics Ltd on behalf of the Cryptix Development Team.
All rights reserved.

$Revision: 1.3 $

Since:

Cryptix 2.2

Author:

Systemics Ltd, David Hopwood

See Also:

cryptix.provider.mode.CFB

Field Summary

protected BlockCipher	cipher Deprecated.
protected int	currentByte Deprecated.
protected byte[]	ivBlock Deprecated.
protected int	length Deprecated.
protected byte[]	xorBlock Deprecated.

Constructor Summary

CipherFeedback(BlockCipher cipher0, byte[] iv0)
Deprecated. This implements variant A: a unique initial value for the feedback register must be provided in the constructor.

Method Summary

void	decrypt(byte[] in, int in_offset, byte[] out, int out_offset, int length) Deprecated. This function decrypts a block of data.
void	encrypt(byte[] in, int in_offset, byte[] out, int out_offset, int length) Deprecated. This function encrypts a block of data.
int	keyLength() Deprecated. This function returns the length of the key for this cipher.
void	reset(byte[] iv0) Deprecated. Reset the stream feedback register with a new unique IV and sets position in stream back to zero.

Methods inherited from class cryptix.security.StreamCipher

decrypt, decrypt, encrypt, encrypt

Methods inherited from class java.lang.Object

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

Field Detail

ivBlock

protected byte[] ivBlock

Deprecated.

xorBlock

protected byte[] xorBlock

Deprecated.

cipher

protected BlockCipher cipher

Deprecated.

currentByte

protected int currentByte

Deprecated.

length

protected int length

Deprecated.

Constructor Detail

CipherFeedback

public CipherFeedback(BlockCipher cipher0,
                      byte[] iv0)

Deprecated.

This implements variant A: a unique initial value for the feedback register must be provided in the constructor. If the IV is not unique, the plaintext can be recovered.

Parameters:

cipher0 - the block cipher to use

iv0 - the initial value for the shift register (IV)

Method Detail

keyLength

public int keyLength()

Deprecated.

Description copied from class: StreamCipher

This function returns the length of the key for this cipher.

Specified by:

keyLength in class StreamCipher

Returns:

the length (in bytes) of the key used with this cipher

reset

public void reset(byte[] iv0)

Deprecated.

Reset the stream feedback register with a new unique IV and sets position in stream back to zero.

Parameters:

iv0 - the initial value for the shift register (IV)

encrypt

public void encrypt(byte[] in,
                    int in_offset,
                    byte[] out,
                    int out_offset,
                    int length)

Deprecated.

This function encrypts a block of data. The contents of the array in will not be changed, but will instead store the result in the array out. The arrays can, however, be the same.

Specified by:

encrypt in class StreamCipher

Parameters:

in - the plain text to be encrypted.

in_offset - the offset within the in buffer.

out - where the encrypted cipher text will be stored.

out_offset - the offset within the out buffer.

length - the length to encrypt.

decrypt

public void decrypt(byte[] in,
                    int in_offset,
                    byte[] out,
                    int out_offset,
                    int length)

Deprecated.

This function decrypts a block of data. The contents of the array in will not be changed, but will instead store the result in the array out. The arrays can, however, be the same.

Specified by:

decrypt in class StreamCipher

Parameters:

in - the cipher text to be decrypted.

in_offset - the offset within the in buffer.

out - where the decrypted plain text will be stored.

out_offset - the offset within the out buffer.

length - the length to decrypt.