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Class cryptix.provider.mode.PCBC

java.lang.Object
   |
   +----java.security.IJCE_Traceable
           |
           +----java.security.Cipher
                   |
                   +----java.security.Mode
                           |
                           +----cryptix.provider.mode.FeedbackMode
                                   |
                                   +----cryptix.provider.mode.PCBC

public class PCBC
extends FeedbackMode
Implements a block cipher in PCBC mode. The block size is the same as that of the underlying cipher.

References:

  1. Bruce Schneier, "Section 9.10 Other Block-Cipher Modes," Applied Cryptography, 2nd edition, John Wiley & Sons, 1996

  2. sci.crypt FAQ, "Part 5: Product Ciphers," ftp://ftp.rtfm.mit.edu/pub/usenet/news.answers/cryptography-faq/part05

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

$Revision: 1.5 $

Author:
David Hopwood, Raif S. Naffah

Constructor Index

 o PCBC()
Constructs a PCBC cipher, assuming that the IV will be provided via setInitializationVector.
 o PCBC(Cipher)
Constructs a PCBC cipher, assuming that the IV will be provided via setInitializationVector.
 o PCBC(Cipher, byte[])
Constructs a PCBC cipher, using an initialization vector provided in the constructor.

Method Index

 o engineBlockSize()
SPI: Returns the length of a block, in bytes.
 o engineInitDecrypt(Key)
SPI: Initializes this cipher for decryption, using the specified key.
 o engineInitEncrypt(Key)
SPI: Initializes this cipher for encryption, using the specified key.
 o engineSetCipher(Cipher)
SPI: Sets the underlying cipher.
 o engineUpdate(byte[], int, int, byte[], int)
SPI: This is the main engine method for updating data.

Constructors

 o PCBC
 public PCBC()
Constructs a PCBC cipher, assuming that the IV will be provided via setInitializationVector.

The IV value should be random, but unlike CFB mode, it is not absolutely required to be unique.

 o PCBC
 public PCBC(Cipher cipher)
Constructs a PCBC cipher, assuming that the IV will be provided via setInitializationVector. See the previous constructor for more details.

Throws: NullPointerException
if cipher == null
Throws: IllegalBlockSizeException
if cipher.getPlaintextBlockSize() != cipher.getCiphertextBlockSize()
 o PCBC
 public PCBC(Cipher cipher,
             byte iv[])
Constructs a PCBC cipher, using an initialization vector provided in the constructor.

The IV value 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.

Parameters:
cipher - the block cipher to use
iv - the initial value for the shift register (IV)
Throws: NullPointerException
if cipher == null

Methods

 o engineSetCipher
 protected void engineSetCipher(Cipher cipher)
SPI: Sets the underlying cipher.

Overrides:
engineSetCipher in class FeedbackMode
 o engineBlockSize
 protected int engineBlockSize()
SPI: Returns the length of a block, in bytes.

Overrides:
engineBlockSize in class Cipher
 o engineInitEncrypt
 protected void engineInitEncrypt(Key newkey) throws KeyException
SPI: Initializes this cipher for encryption, using the specified key.

Overrides:
engineInitEncrypt in class Cipher
 o engineInitDecrypt
 protected void engineInitDecrypt(Key newkey) throws KeyException
SPI: Initializes this cipher for decryption, using the specified key.

Overrides:
engineInitDecrypt in class Cipher
 o engineUpdate
 protected int engineUpdate(byte in[],
                            int inOffset,
                            int inLen,
                            byte out[],
                            int outOffset)
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.

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.
Overrides:
engineUpdate in class Cipher

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