org.bouncycastle.crypto.modes
Class PGPCFBBlockCipher

java.lang.Object
  org.bouncycastle.crypto.modes.PGPCFBBlockCipher

All Implemented Interfaces:

BlockCipher

public class PGPCFBBlockCipher
extends java.lang.Object
implements BlockCipher

Implements OpenPGP's rather strange version of Cipher-FeedBack (CFB) mode on top of a simple cipher. For further info see RFC 2440.

Field Summary

private int	blockSize
private BlockCipher	cipher
private int	count
private boolean	forEncryption
private byte[]	FR
private byte[]	FRE
private boolean	inlineIv
private byte[]	IV
private byte[]	tmp

Constructor Summary

PGPCFBBlockCipher(BlockCipher cipher, boolean inlineIv)
Basic constructor.

Method Summary

private int	decryptBlock(byte[] in, int inOff, byte[] out, int outOff) Do the appropriate processing for CFB mode decryption.
private int	decryptBlockWithIV(byte[] in, int inOff, byte[] out, int outOff) Do the appropriate processing for CFB IV mode decryption.
private int	encryptBlock(byte[] in, int inOff, byte[] out, int outOff) Do the appropriate processing for CFB mode encryption.
private int	encryptBlockWithIV(byte[] in, int inOff, byte[] out, int outOff) Do the appropriate processing for CFB IV mode encryption.
private byte	encryptByte(byte data, int blockOff) Encrypt one byte of data according to CFB mode.
java.lang.String	getAlgorithmName() return the algorithm name and mode.
int	getBlockSize() return the block size we are operating at.
BlockCipher	getUnderlyingCipher() return the underlying block cipher that we are wrapping.
void	init(boolean forEncryption, CipherParameters params) Initialise the cipher and, possibly, the initialisation vector (IV).
int	processBlock(byte[] in, int inOff, byte[] out, int outOff) Process one block of input from the array in and write it to the out array.
void	reset() reset the chaining vector back to the IV and reset the underlying cipher.

Methods inherited from class java.lang.Object

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

Field Detail

IV

private byte[] IV

FR

private byte[] FR

FRE

private byte[] FRE

tmp

private byte[] tmp

cipher

private BlockCipher cipher

count

private int count

blockSize

private int blockSize

forEncryption

private boolean forEncryption

inlineIv

private boolean inlineIv

Constructor Detail

PGPCFBBlockCipher

public PGPCFBBlockCipher(BlockCipher cipher,
                         boolean inlineIv)

Basic constructor.

Parameters:

cipher - the block cipher to be used as the basis of the feedback mode.

inlineIv - if true this is for PGP CFB with a prepended iv.

Method Detail

getUnderlyingCipher

public BlockCipher getUnderlyingCipher()

return the underlying block cipher that we are wrapping.

Returns:

the underlying block cipher that we are wrapping.

getAlgorithmName

public java.lang.String getAlgorithmName()

return the algorithm name and mode.

Specified by:

getAlgorithmName in interface BlockCipher

Returns:

the name of the underlying algorithm followed by "/PGPCFB" and the block size in bits.

getBlockSize

public int getBlockSize()

return the block size we are operating at.

Specified by:

getBlockSize in interface BlockCipher

Returns:

the block size we are operating at (in bytes).

processBlock

public int processBlock(byte[] in,
                        int inOff,
                        byte[] out,
                        int outOff)
                 throws DataLengthException,
                        java.lang.IllegalStateException

Process one block of input from the array in and write it to the out array.

Specified by:

processBlock in interface BlockCipher

Parameters:

in - the array containing the input data.

inOff - offset into the in array the data starts at.

out - the array the output data will be copied into.

outOff - the offset into the out array the output will start at.

Returns:

the number of bytes processed and produced.

Throws:

DataLengthException - if there isn't enough data in in, or space in out.

java.lang.IllegalStateException - if the cipher isn't initialised.

reset

public void reset()

reset the chaining vector back to the IV and reset the underlying cipher.

Specified by:

reset in interface BlockCipher

init

public void init(boolean forEncryption,
                 CipherParameters params)
          throws java.lang.IllegalArgumentException

Initialise the cipher and, possibly, the initialisation vector (IV). If an IV isn't passed as part of the parameter, the IV will be all zeros. An IV which is too short is handled in FIPS compliant fashion.

Specified by:

init in interface BlockCipher

Parameters:

forEncryption - if true the cipher is initialised for encryption, if false for decryption.

params - the key and other data required by the cipher.

Throws:

java.lang.IllegalArgumentException - if the params argument is inappropriate.

encryptByte

private byte encryptByte(byte data,
                         int blockOff)

Encrypt one byte of data according to CFB mode.

Parameters:

data - the byte to encrypt

where - am i in the current block, determines when to resync the block

encryptBlockWithIV

private int encryptBlockWithIV(byte[] in,
                               int inOff,
                               byte[] out,
                               int outOff)
                        throws DataLengthException,
                               java.lang.IllegalStateException

Do the appropriate processing for CFB IV mode encryption.

Parameters:

in - the array containing the data to be encrypted.

inOff - offset into the in array the data starts at.

out - the array the encrypted data will be copied into.

outOff - the offset into the out array the output will start at.

Returns:

the number of bytes processed and produced.

Throws:

DataLengthException - if there isn't enough data in in, or space in out.

java.lang.IllegalStateException - if the cipher isn't initialised.

decryptBlockWithIV

private int decryptBlockWithIV(byte[] in,
                               int inOff,
                               byte[] out,
                               int outOff)
                        throws DataLengthException,
                               java.lang.IllegalStateException

Do the appropriate processing for CFB IV mode decryption.

Parameters:

in - the array containing the data to be decrypted.

inOff - offset into the in array the data starts at.

out - the array the encrypted data will be copied into.

outOff - the offset into the out array the output will start at.

Returns:

the number of bytes processed and produced.

Throws:

DataLengthException - if there isn't enough data in in, or space in out.

java.lang.IllegalStateException - if the cipher isn't initialised.

encryptBlock

private int encryptBlock(byte[] in,
                         int inOff,
                         byte[] out,
                         int outOff)
                  throws DataLengthException,
                         java.lang.IllegalStateException

Do the appropriate processing for CFB mode encryption.

Parameters:

in - the array containing the data to be encrypted.

inOff - offset into the in array the data starts at.

out - the array the encrypted data will be copied into.

outOff - the offset into the out array the output will start at.

Returns:

the number of bytes processed and produced.

Throws:

DataLengthException - if there isn't enough data in in, or space in out.

java.lang.IllegalStateException - if the cipher isn't initialised.

decryptBlock

private int decryptBlock(byte[] in,
                         int inOff,
                         byte[] out,
                         int outOff)
                  throws DataLengthException,
                         java.lang.IllegalStateException

Do the appropriate processing for CFB mode decryption.

Parameters:

in - the array containing the data to be decrypted.

inOff - offset into the in array the data starts at.

out - the array the encrypted data will be copied into.

outOff - the offset into the out array the output will start at.

Returns:

the number of bytes processed and produced.

Throws:

DataLengthException - if there isn't enough data in in, or space in out.

java.lang.IllegalStateException - if the cipher isn't initialised.