cryptix.provider.cipher

Class Blowfish

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 $

Since: Cryptix 2.2

Author: Systemics Ltd David Hopwood Raif S. Naffah

Constructor Summary
Blowfish()
Constructs a Blowfish cipher object, in the UNINITIALIZED state.
Method Summary
Objectclone()
Always throws a CloneNotSupportedException (cloning of ciphers is not supported for security reasons).
protected intengineBlockSize()
SPI: Returns the length of an input block, in bytes.
protected ObjectengineGetParameter(String param)
SPI: Gets the value of the specified algorithm parameter.
protected voidengineInitDecrypt(Key key)
SPI: Initializes this cipher for decryption, using the specified key.
protected voidengineInitEncrypt(Key key)
SPI: Initializes this cipher for encryption, using the specified key.
protected voidengineSetParameter(String param, Object value)
SPI: Sets the specified algorithm parameter to the specified value.
protected intengineUpdate(byte[] in, int inOffset, int inLen, byte[] out, int outOffset)
SPI: This is the main engine method for updating data.
protected voidfinalize()
Cleans up resources used by this instance, if necessary.
static LinkStatusgetLinkStatus()
Gets an object representing the native linking status of this class.
intgetRounds()
Returns the currently set number of rounds for this instance.
static voidmain(String[] args)
Entry point for very basic self_test.
voidsetRounds(int r)
Sets the number of rounds for this cipher.

Constructor Detail

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.

Throws: CryptixException if a CRC check fails on the initial values of the S and P boxes.

Method Detail

clone

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

engineBlockSize

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

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.

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)
SPI: Initializes this cipher for decryption, using the specified key.

Parameters: key the key to use for decryption.

Throws: InvalidKeyException when one of the following occurs:

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)
SPI: Initializes this cipher for encryption, using the specified key.

Parameters: key the key to use for encryption.

Throws: InvalidKeyException when one of the following occurs:

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)
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.

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

Throws: InvalidParameterException if param is an invalid parameter for this cipher implementation, the parameter is already set and cannot be set again, a security exception occurs, and so on. 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.

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.

Throws: CryptixException if the native library is being used, and it reports an error.

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.

Throws: IllegalArgumentException if the given number of rounds is not supported.

UNKNOWN: IllegalStateException if this cipher is not uninitialised.