cryptix.security
Class CFB

java.lang.Object
  cryptix.security.StreamCipher
      cryptix.security.CFB

Direct Known Subclasses:

PGPCFB

public class CFB

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 int	blocksize Deprecated.
protected int	bytesLeft Deprecated.
protected BlockCipher	cipher Deprecated.
protected byte[]	iv Deprecated.
protected byte[]	k Deprecated.

Constructor Summary

CFB(BlockCipher cipher0)
Deprecated. This implements variant B: a unique IV for the feedback register must be provided as the first blockLength characters in the stream.

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	next_block() Deprecated.
void	reset() Deprecated. Reset the stream and the IV.

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

cipher

protected BlockCipher cipher

Deprecated.

blocksize

protected int blocksize

Deprecated.

iv

protected byte[] iv

Deprecated.

k

protected byte[] k

Deprecated.

bytesLeft

protected int bytesLeft

Deprecated.

Constructor Detail

CFB

public CFB(BlockCipher cipher0)

Deprecated.

This implements variant B: a unique IV for the feedback register must be provided as the first blockLength characters in the stream. If the IV is not unique, the plaintext can be recovered.

Parameters:

cipher0 - the block cipher to use

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

next_block

public void next_block()

Deprecated.

reset

public void reset()

Deprecated.

Reset the stream and the IV. Note that a new IV is now needed as described above.

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 remain unchanged, with the result stored 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.