cryptix.provider.cipher

Class SAFER

public final class SAFER extends Cipher implements SymmetricCipher

A subclass of Cipher to implement the SAFER algorithm in Java.

SAFER (Secure And Fast Encryption Routine) is a block-cipher algorithm developed by Prof. J.L. Massey at the Swiss Federal Institute of Technology. SAFER is usable in four versions (referred to in this implementation as VARIANTS): SAFER K-64, SAFER K-128, SAFER SK-64 and SAFER SK-128. The numerals 64 and 128 stand for the length of the user-selected key, 'K' stands for the original key schedule and 'SK' stands for the strengthened key schedule.

References:

  1. Massey, J.L., "SAFER K-64: A Byte-Oriented Block Ciphering Algorithm", pp. 1-17 in Fast Software Encryption (Ed. R. Anderson), Proceedings of the Cambridge Security Workshop, Cambridge, U.K., December 9-11, 1993,
    Lecture Notes in Computer Science No. 809. Heidelberg and New York: Springer, 1994.

  2. Massey, J.L., "SAFER K-64: One Year Later", preliminary manuscript of a paper presented at the K. U. Leuven Workshop on Cryptographic Algorithms, December 14-16, 1994.
    To be published in the Proceedings of this workshop by Springer.

  3. Massey, J.L., "Announcement of a Strengthened Key Schedule for the Cipher SAFER", Sept. 9, 1995, (see file 'SAFER_SK.TXT' included in the toolkit).

  4. Richard De Moliner <demoliner@isi.ee.ethz.ch> SAFER toolkit V1.2 includes C implementation, additional notes, test data, test program.

Ported to Java from public domain 'C' code latest revised on September 9, 1995 by:

Richard De Moliner (demoliner@isi.ee.ethz.ch)
Signal and Information Processing Laboratory
Swiss Federal Institute of Technology
CH-8092 Zürich, Switzerland.

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

$Revision: 1.8 $

Since: Cryptix 2.2.2

Author: Raif S. Naffah David Hopwood

Field Summary
static intK128_VARIANT
static intK64_VARIANT
static intSK128_VARIANT
static intSK64_VARIANT
Constructor Summary
SAFER()
Calls the Cipher constructor with implBuffering false, implPadding false and the provider set to "Cryptix".
Method Summary
Objectclone()
Always throws a CloneNotSupportedException (cloning of ciphers is not supported for security reasons).
intengineBlockSize()
SPI: Returns the length of an input block, in bytes.
protected ObjectengineGetParameter(String param)
voidengineInitDecrypt(Key key)
SPI: Initializes this cipher for decryption, using the specified key.
voidengineInitEncrypt(Key key)
SPI: Initializes this cipher for encryption, using the specified key.
protected voidengineSetParameter(String param, Object 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()
Gets the number of rounds for this cipher.
StringgetVariant()
Gets the variant for this cipher ("SK-128", "SK-64", "K-128", or "K-64").
voidsetRounds(int rounds)
Sets the number of rounds for this cipher.
voidsetVariant(String ps)
Sets the variant for this cipher.

Field Detail

K128_VARIANT

public static final int K128_VARIANT

K64_VARIANT

public static final int K64_VARIANT

SK128_VARIANT

public static final int SK128_VARIANT

SK64_VARIANT

public static final int SK64_VARIANT

Constructor Detail

SAFER

public SAFER()
Calls the Cipher constructor with implBuffering false, implPadding false and the provider set to "Cryptix".

Sets the variant of this cipher based on the currently set "variant" property in the provider properties file. The current JCE syntax for the SAFER algorithm variant property is:

    Alg.variant.SAFER = ...
 

Valid alternatives for variant are:

Once the variant is set, a default value for the number of rounds to use is also set as follows:

    Variant   Number of rounds = current value
    -------   --------------------------------
    SK-128    SK128_DEFAULT_NOF_ROUNDS = 10
    SK-64     SK64_DEFAULT_NOF_ROUNDS  =  8
    K-128     K128_DEFAULT_NOF_ROUNDS  = 10
    K-64      K64_DEFAULT_NOF_ROUNDS   =  6
 

If no variant property is found in the provider's properties file a strengthened key schedule of 128 bits is used with 10 rounds.

This constructor also attempts to set the desired number of rounds for this cipher object from a "rounds" property in the provider's properties file. Acceptable values are non-zero integers between 1 and the MAX_NOF_ROUNDS constant; i.e. 13. If no such property is found, or is found but deemed invalid, then the already set value (depending on the variant property as determined above) remains unaltered.

Method Detail

clone

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

engineBlockSize

public 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)

engineInitDecrypt

public void engineInitDecrypt(Key key)
SPI: Initializes this cipher for decryption, using the specified key.

Parameters: key the key to use for decryption.

Throws: KeyException if the key is invalid.

engineInitEncrypt

public void engineInitEncrypt(Key key)
SPI: Initializes this cipher for encryption, using the specified key.

Parameters: key the key to use for encryption.

Throws: KeyException if the key is invalid.

engineSetParameter

protected void engineSetParameter(String param, Object value)

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()
Gets the number of rounds for this cipher.

getVariant

public String getVariant()
Gets the variant for this cipher ("SK-128", "SK-64", "K-128", or "K-64").

setRounds

public void setRounds(int rounds)
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, the current one remains unchanged.

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

UNKNOWN: IllegalStateException if this cipher is not uninitialised.

setVariant

public void setVariant(String ps)
Sets the variant for this cipher. Allowed only when this cipher is in the UNINITIALIZED state; otherwise an exception is thrown.

Parameters: ps The desired new variant identifier for this cipher.

UNKNOWN: IllegalStateException If this cipher is not uninitialised. InvalidParameterException If the variant identifier is invalid.