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.
Overrides:
keyLength in class StreamCipher
Following copied from class: cryptix.security.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.
Overrides:
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.
Overrides:
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.