cryptix.provider.cipher

Class Blowfish

Implemented Interfaces:
Parameterized, SymmetricCipher

public final class Blowfish
extends Cipher
implements SymmetricCipher

This class implements the Blowfish block cipher.

Blowfish was designed by Bruce Schneier. The algorithm is in the public domain.

References:

  1. Bruce Schneier, "Section 14.3 Blowfish," Applied Cryptography, 2nd edition, John Wiley & Sons, 1996

  2. Bruce Schneier, "Description of a New Variable-Length Key, 64-Bit Cipher (Blowfish)," Fast Software Encryption Cambridge Security Workshop Proceedings, Springer-Verlag, 1004, pp 191-204.

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

$Revision: 1.8 $

Authors:
Systemics Ltd
David Hopwood
Raif S. Naffah

Since:
Cryptix 2.2

Field Summary

Fields inherited from class xjava.security.Cipher

DECRYPT, ENCRYPT, UNINITIALIZED

Fields inherited from class xjava.security.IJCE_Traceable

tracing

Constructor Summary

Blowfish()
Constructs a Blowfish cipher object, in the UNINITIALIZED state.

Method Summary

Object
clone()
Always throws a CloneNotSupportedException (cloning of ciphers is not supported for security reasons).
protected int
engineBlockSize()
SPI: Returns the length of an input block, in bytes.
protected Object
engineGetParameter(String param)
SPI: Gets the value of the specified algorithm parameter.
protected void
engineInitDecrypt(Key key)
SPI: Initializes this cipher for decryption, using the specified key.
protected void
engineInitEncrypt(Key key)
SPI: Initializes this cipher for encryption, using the specified key.
protected void
engineSetParameter(String param, Object value)
SPI: Sets the specified algorithm parameter to the specified value.
protected int
engineUpdate(byte[] in, int inOffset, int inLen, byte[] out, int outOffset)
SPI: This is the main engine method for updating data.
protected void
finalize()
Cleans up resources used by this instance, if necessary.
static LinkStatus
getLinkStatus()
Gets an object representing the native linking status of this class.
int
getRounds()
Returns the currently set number of rounds for this instance.
static void
main(String[] args)
Entry point for very basic self_test.
void
setRounds(int r)
Sets the number of rounds for this cipher.

Methods inherited from class xjava.security.Cipher

blockSize, clone, crypt, crypt, crypt, doFinal, doFinal, doFinal, doFinal, engineBlockSize, engineCiphertextBlockSize, engineCrypt, engineGetParameter, engineInBufferSize, engineInitDecrypt, engineInitEncrypt, engineOutBufferSize, enginePlaintextBlockSize, engineSetPaddingScheme, engineSetParameter, engineUpdate, getAlgorithm, getAlgorithms, getAlgorithms, getCiphertextBlockSize, getInputBlockSize, getInstance, getInstance, getInstance, getMode, getOutputBlockSize, getPadding, getPaddingScheme, getParameter, getPlaintextBlockSize, getProvider, getState, inBufferSize, inBufferSizeFinal, initDecrypt, initEncrypt, isPaddingBlockCipher, outBufferSize, outBufferSizeFinal, setParameter, toString, update, update, update, update

Methods inherited from class xjava.security.IJCE_Traceable

disableTracing, enableTracing, traceMethod, traceResult, traceResult, traceVoidMethod

Constructor Details

Blowfish

public Blowfish()
Constructs a Blowfish cipher object, in the UNINITIALIZED state. This calls the Cipher constructor with implBuffering false, implPadding false and the provider set to "Cryptix".

We define a "rounds" property to allow running the algorithm in a number of rounds different than the default value; i.e. 16. Note however that there is not enough defined initial data for any number of rounds other than 16 for the time being.

Method Details

clone

public final Object clone()
            throws CloneNotSupportedException
Always throws a CloneNotSupportedException (cloning of ciphers is not supported for security reasons).
Overrides:
clone in interface Cipher


engineBlockSize

protected int engineBlockSize()
SPI: Returns the length of an input block, in bytes.
Overrides:
engineBlockSize in interface Cipher

Returns:
the length in bytes of an input block for this cipher.


engineGetParameter

protected Object engineGetParameter(String param)
SPI: Gets the value of the specified algorithm parameter.

Blowfish has a single parameter, "rounds", which specifies the number of rounds for this instance as a decimal String.

Overrides:
engineGetParameter in interface Cipher

Parameters:
param - the string name of the parameter.

Returns:
the object that represents the parameter value, or null if there is none.


engineInitDecrypt

protected void engineInitDecrypt(Key key)
            throws InvalidKeyException,
                   CryptixException
SPI: Initializes this cipher for decryption, using the specified key.
Overrides:
engineInitDecrypt in interface Cipher

Parameters:
key - the key to use for decryption.

Throws:
CryptixException - if any one of the two self-tests fail. The two self-tests are as follows:
  1. encrypt 0 ten times using the initial S and P boxes values. Check the result against a known value. If equal decrypt the result 10 times and compare it to 0;
  2. complete the key expansion process and use the newly formed key to encrypt 10 times 0; decrypt the result 10 times and compare.


engineInitEncrypt

protected void engineInitEncrypt(Key key)
            throws InvalidKeyException,
                   CryptixException
SPI: Initializes this cipher for encryption, using the specified key.
Overrides:
engineInitEncrypt in interface Cipher

Parameters:
key - the key to use for encryption.

Throws:
CryptixException - if any one of the two self-tests fail. The two self-tests are as follows:
  1. encrypt 0 ten times using the initial S and P boxes values. Check the result against a known value. If equal decrypt the result 10 times and compare it to 0;
  2. complete the key expansion process and use the newly formed key to encrypt 10 times 0; decrypt the result 10 times and compare.


engineSetParameter

protected void engineSetParameter(String param,
                                  Object value)
            throws InvalidParameterException,
                   InvalidParameterTypeException
SPI: Sets the specified algorithm parameter to the specified value.

Blowfish has a single parameter, "rounds", which specifies the number of rounds for this instance as a decimal String.

Overrides:
engineSetParameter in interface Cipher

Parameters:
param - the string name of the parameter.
value - the parameter value.

Throws:
InvalidParameterTypeException - if value is of the wrong type.


engineUpdate

protected int engineUpdate(byte[] in,
                           int inOffset,
                           int inLen,
                           byte[] out,
                           int outOffset)
SPI: This is the main engine method for updating data.

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

Overrides:
engineUpdate in interface Cipher

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.


finalize

protected final void finalize()
Cleans up resources used by this instance, if necessary.


getLinkStatus

public static LinkStatus getLinkStatus()
Gets an object representing the native linking status of this class.


getRounds

public int getRounds()
Returns the currently set number of rounds for this instance.

Returns:
the number of rounds.


main

public static void main(String[] args)
Entry point for very basic self_test.


setRounds

public void setRounds(int r)
Sets the number of rounds for this cipher. Allowed only when this cipher is in the UNINITIALIZED state; otherwise an exception is thrown.

If the specified number is invalid, an IllegalArgumentException is thrown.

Note that there is not enough defined initial data for any number of rounds other than 16 for the time being.

Parameters:
r - the desired number of rounds for this cipher.