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gnu.javax.crypto.assembly

Class Cascade

public class Cascade
extends Object
A Cascade Cipher is the concatenation of two or more block ciphers each with independent keys. Plaintext is input to the first stage; the output of stage i is input to stage i + 1; and the output of the last stage is the Cascade's ciphertext output.

In the simplest case, all stages in a Cascade have k-bit keys, and the stage inputs and outputs are all n-bit quantities. The stage ciphers may differ (general cascade of ciphers), or all be identical (cascade of identical ciphers).

The term "block ciphers" used above refers to implementations of IMode, including the ECB mode which basically exposes a symmetric-key block cipher algorithm as a Mode of Operations.

References:

  1. [HAC]: Handbook of Applied Cryptography.
    CRC Press, Inc. ISBN 0-8493-8523-7, 1997
    Menezes, A., van Oorschot, P. and S. Vanstone.

Field Summary

static String
DIRECTION
protected int
blockSize
The curently set block-size for this instance.
protected LinkedList<T>
stageKeys
The ordered list of Stage UIDs to their attribute maps.
protected HashMap<K,V>
stages
The map of Stages chained in this cascade.
protected Direction
wired
The current operational direction of this instance.

Constructor Summary

Cascade()
The basic constructor.

Method Summary

Object
append(Stage stage)
Adds to the end of the current chain, a designated Stage.
Set<E>
blockSizes()
Returns the Set of supported block sizes for this Cascade that are common to all of its chained stages.
int
currentBlockSize()
Returns the currently set block size for the chain.
void
init(Map<K,V> attributes)
Initialises the chain for operation with specific characteristics.
Object
insert(int index, Stage stage)
Inserts a Stage into the current chain, at the specified index (zero-based) position.
Object
prepend(Stage stage)
Adds to the begining of the current chain, a designated Stage.
void
reset()
Resets the chain for re-initialisation and use with other characteristics.
boolean
selfTest()
Conducts a simple correctness test that consists of basic symmetric encryption / decryption test(s) for all supported block and key sizes of underlying block cipher(s) wrapped by Mode leafs.
int
size()
Returns the current number of stages in this chain.
Iterator<E>
stages()
Returns an Iterator over the stages contained in this instance.
void
update(byte[] in, int inOffset, byte[] out, int outOffset)
Processes exactly one block of plaintext (if initialised in the Direction.FORWARD state) or ciphertext (if initialised in the Direction.REVERSED state).

Methods inherited from class java.lang.Object

clone, equals, extends Object> getClass, finalize, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Details

DIRECTION

public static final String DIRECTION
Field Value:
"gnu.crypto.assembly.cascade.direction"

blockSize

protected int blockSize
The curently set block-size for this instance.

stageKeys

protected LinkedList<T> stageKeys
The ordered list of Stage UIDs to their attribute maps.

stages

protected HashMap<K,V> stages
The map of Stages chained in this cascade.

wired

protected Direction wired
The current operational direction of this instance.

Constructor Details

Cascade

public Cascade()
The basic constructor. Object is special, because it has no superclass, so there is no call to super().

Method Details

append

public Object append(Stage stage)
            throws IllegalArgumentException
Adds to the end of the current chain, a designated Stage.
Parameters:
stage - the Stage to append to the chain.
Returns:
a unique identifier for this stage, within this cascade.
Throws:
IllegalStateException - if the instance is already initialised.
IllegalArgumentException - if the designated stage is already in the chain, or it has incompatible characteristics with the current elements already in the chain.

blockSizes

public Set<E> blockSizes()
Returns the Set of supported block sizes for this Cascade that are common to all of its chained stages. Each element in the returned Set is an instance of Integer.
Returns:
a Set of supported block sizes common to all the stages of the chain.

currentBlockSize

public int currentBlockSize()
Returns the currently set block size for the chain.
Returns:
the current block size for the chain.
Throws:
IllegalStateException - if the instance is not initialised.

init

public void init(Map<K,V> attributes)
            throws InvalidKeyException
Initialises the chain for operation with specific characteristics.
Parameters:
attributes - a set of name-value pairs that describes the desired future behaviour of this instance.
Throws:
IllegalStateException - if the chain, or any of its stages, is already initialised.
InvalidKeyException - if the intialisation data provided with the stage is incorrect or causes an invalid key to be generated.
See Also:
Direction.FORWARD, Direction.REVERSED

insert

public Object insert(int index,
                     Stage stage)
            throws IllegalArgumentException,
                   IndexOutOfBoundsException
Inserts a Stage into the current chain, at the specified index (zero-based) position.
Parameters:
stage - the Stage to insert into the chain.
Returns:
a unique identifier for this stage, within this cascade.
Throws:
IllegalArgumentException - if the designated stage is already in the chain, or it has incompatible characteristics with the current elements already in the chain.
IllegalStateException - if the instance is already initialised.
IndexOutOfBoundsException - if index is less than 0 or greater than the current size of this cascade.

prepend

public Object prepend(Stage stage)
            throws IllegalArgumentException
Adds to the begining of the current chain, a designated Stage.
Parameters:
stage - the Stage to prepend to the chain.
Returns:
a unique identifier for this stage, within this cascade.
Throws:
IllegalStateException - if the instance is already initialised.
IllegalArgumentException - if the designated stage is already in the chain, or it has incompatible characteristics with the current elements already in the chain.

reset

public void reset()
Resets the chain for re-initialisation and use with other characteristics. This method always succeeds.

selfTest

public boolean selfTest()
Conducts a simple correctness test that consists of basic symmetric encryption / decryption test(s) for all supported block and key sizes of underlying block cipher(s) wrapped by Mode leafs. The test also includes one (1) variable key Known Answer Test (KAT) for each block cipher.
Returns:
true if the implementation passes simple correctness tests. Returns false otherwise.

size

public int size()
Returns the current number of stages in this chain.
Returns:
the current count of stages in this chain.

stages

public Iterator<E> stages()
Returns an Iterator over the stages contained in this instance. Each element of this iterator is a concrete implementation of a Stage.
Returns:
an Iterator over the stages contained in this instance. Each element of the returned iterator is a concrete instance of a Stage.

update

public void update(byte[] in,
                   int inOffset,
                   byte[] out,
                   int outOffset)
Processes exactly one block of plaintext (if initialised in the Direction.FORWARD state) or ciphertext (if initialised in the Direction.REVERSED state).
Parameters:
in - the plaintext.
inOffset - index of in from which to start considering data.
out - the ciphertext.
outOffset - index of out from which to store result.
Throws:
IllegalStateException - if the instance is not initialised.
Cascade.java -- Copyright (C) 2003, 2006 Free Software Foundation, Inc. This file is a part of GNU Classpath. GNU Classpath is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. GNU Classpath is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with GNU Classpath; if not, write to the Free Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA Linking this library statically or dynamically with other modules is making a combined work based on this library. Thus, the terms and conditions of the GNU General Public License cover the whole combination. As a special exception, the copyright holders of this library give you permission to link this library with independent modules to produce an executable, regardless of the license terms of these independent modules, and to copy and distribute the resulting executable under terms of your choice, provided that you also meet, for each linked independent module, the terms and conditions of the license of that module. An independent module is a module which is not derived from or based on this library. If you modify this library, you may extend this exception to your version of the library, but you are not obligated to do so. If you do not wish to do so, delete this exception statement from your version.

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