cryptix.provider.mode
Class CFB_PGP

java.lang.Object
  |
  +--xjava.security.IJCE_Traceable
        |
        +--xjava.security.Cipher
              |
              +--xjava.security.Mode
                    |
                    +--cryptix.provider.mode.FeedbackMode
                          |
                          +--cryptix.provider.mode.CFB
                                |
                                +--cryptix.provider.mode.CFB_PGP
All Implemented Interfaces:
FeedbackCipher, Parameterized, SymmetricCipher

public class CFB_PGP
extends CFB

Use of this feedback mode is deprecated, use it for compatibility only!

This class implements PGP's (i.e. Zimmerman's) non-standard CFB mode. (For the standard method, see the Applied Cryptography reference below). It replaces cryptix.pgp.CFB in version 2.2, and cryptix.pgp.PGP_CFB in version Cryptix 2.2.0a.

The differences between this and standard CFB are that:

Note that it is unusual for the output of a cipher to depend on the exact boundaries between data passed to each encryption/decryption call. Normally, the lengths of data passed to each call do not matter as long as they make up the correct input when concatenated together - but this class is an exception.

As a result, using this mode with CipherInputStream and CipherOutputStream may produce unexpected output, and is not recommended.

References

  1. Bruce Schneier, "Section 9.6 Cipher Feedback Mode," Applied Cryptography, 2nd edition, John Wiley & Sons, 1996

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

$Revision: 1.9 $

Since:
Cryptix 2.2.2
Author:
Systemics Ltd, Raif Naffah, David Hopwood

Fields inherited from class cryptix.provider.mode.FeedbackMode
currentByte, ivBlock, ivStart, length
 
Fields inherited from class xjava.security.Mode
cipher
 
Fields inherited from class xjava.security.Cipher
DECRYPT, ENCRYPT, UNINITIALIZED
 
Fields inherited from class xjava.security.IJCE_Traceable
tracing
 
Constructor Summary
CFB_PGP()
          Constructs a CFB-PGP cipher, assuming that the IV will be provided as the first getInitializationVectorLength() bytes of the stream (it will be visible as cleartext at the start of the output stream).
CFB_PGP(Cipher cipher)
          Constructs a CFB-PGP cipher, assuming that the IV will be provided as the first getInitializationVectorLength() bytes of the stream.
 
Method Summary
protected  int engineUpdate(byte[] in, int inOffset, int inLen, byte[] out, int outOffset)
          SPI: This is the main engine method for updating data.
 
Methods inherited from class cryptix.provider.mode.CFB
engineBlockSize, engineInitDecrypt, engineInitEncrypt, engineSetCipher, next_block
 
Methods inherited from class cryptix.provider.mode.FeedbackMode
getInitializationVector, getInitializationVectorLength, setInitializationVector
 
Methods inherited from class xjava.security.Mode
engineGetParameter, engineSetParameter, getAlgorithms, getAlgorithms, getInstance, getInstance, toString
 
Methods inherited from class xjava.security.Cipher
blockSize, clone, crypt, crypt, crypt, doFinal, doFinal, doFinal, doFinal, engineCiphertextBlockSize, engineCrypt, engineInBufferSize, engineOutBufferSize, enginePlaintextBlockSize, engineSetPaddingScheme, getAlgorithm, getCiphertextBlockSize, getInputBlockSize, getInstance, getMode, getOutputBlockSize, getPadding, getPaddingScheme, getParameter, getPlaintextBlockSize, getProvider, getState, inBufferSize, inBufferSizeFinal, initDecrypt, initEncrypt, isPaddingBlockCipher, outBufferSize, outBufferSizeFinal, setParameter, update, update, update, update
 
Methods inherited from class xjava.security.IJCE_Traceable
, disableTracing, enableTracing, traceMethod, traceResult, traceResult, traceVoidMethod
 
Methods inherited from class java.lang.Object
equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
 

Constructor Detail

CFB_PGP

public CFB_PGP()
Constructs a CFB-PGP cipher, assuming that the IV will be provided as the first getInitializationVectorLength() bytes of the stream (it will be visible as cleartext at the start of the output stream).

The IV must be unique during the lifetime of the key. If it is not unique, at least the first block of the plaintext can be recovered.


CFB_PGP

public CFB_PGP(Cipher cipher)
Constructs a CFB-PGP cipher, assuming that the IV will be provided as the first getInitializationVectorLength() bytes of the stream. See the previous constructor for more details.
Throws:
NullPointerException - if cipher == null
IllegalBlockSizeException - if cipher.getPlaintextBlockSize() != cipher.getCiphertextBlockSize()
Method Detail

engineUpdate

protected int engineUpdate(byte[] in,
                           int inOffset,
                           int inLen,
                           byte[] out,
                           int outOffset)
Description copied from class: CFB
SPI: This is the main engine method for updating data. It may be called with any size of input.

in and out may be the same array, and the input and output regions may overlap.

Overrides:
engineUpdate in class CFB
Following copied from class: cryptix.provider.mode.CFB
Parameters:
in - the input data.
inOffset - the offset into in specifying where the data starts.
inLen - the length of the subarray.
out - the output array.
outOffset - the offset indicating where to start writing into the out array.
Returns:
the number of bytes written.