gnu.crypto.assembly
Class Cascade
java.lang.Object
gnu.crypto.assembly.Cascade
public class Cascade
extends java.lang.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:
- [HAC]: Handbook of
Applied Cryptography.
CRC Press, Inc. ISBN 0-8493-8523-7, 1997
Menezes, A., van Oorschot, P. and S. Vanstone.
Version:
static String | DIRECTION
|
protected int | blockSize - The curently set block-size for this instance.
|
protected LinkedList | stageKeys - The ordered list of Stage UIDs to their attribute maps.
|
protected HashMap | stages - The map of Stages chained in this cascade.
|
protected Direction | wired - The current operational direction of this instance.
|
Object | append(Stage stage) - Adds to the end of the current chain, a designated
Stage .
|
Set | 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 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 | 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).
|
DIRECTION
public static final String DIRECTION
blockSize
protected int blockSize
The curently set block-size for this instance.
stageKeys
protected LinkedList stageKeys
The ordered list of Stage UIDs to their attribute maps.
stages
protected HashMap stages
The map of Stages chained in this cascade.
wired
protected Direction wired
The current operational direction of this instance.
append
public Object append(Stage stage)
throws IllegalArgumentException
Adds to the end of the current chain, a designated
Stage
.
stage
- the Stage
to append to the chain.
- a unique identifier for this stage, within this cascade.
blockSizes
public Set 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
.
- 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.
- the current block size for the chain.
init
public void init(Map attributes)
throws InvalidKeyException
Initialises the chain for operation with specific characteristics.
attributes
- a set of name-value pairs that describes the desired
future behaviour of this instance.
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.
stage
- the Stage
to insert into the chain.
- a unique identifier for this stage, within this cascade.
prepend
public Object prepend(Stage stage)
throws IllegalArgumentException
Adds to the begining of the current chain, a designated
Stage
.
stage
- the Stage
to prepend to the chain.
- a unique identifier for this stage, within this cascade.
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.
true
if the implementation passes simple
correctness tests. Returns false
otherwise.
size
public int size()
Returns the current number of stages in this chain.
- the current count of stages in this chain.
stages
public Iterator stages()
Returns an
Iterator
over the stages contained in this instance.
Each element of this iterator is a concrete implementation of a
Stage
.
- 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)
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.
Copyright © 2001, 2002, 2003
Free Software Foundation,
Inc. All Rights Reserved.