gnu.crypto.assembly

Class Stage

Known Direct Subclasses:
CascadeStage, ModeStage

public abstract class Stage
extends Object

A Stage in a Cascade Cipher.

Each stage may be either an implementation of a Block Cipher Mode of Operation (IMode) or another Cascade Cipher (Cascade). Each stage has also a natural operational direction when constructed for inclusion within a Cascade. This natural direction dictates how data flows from one stage into another when stages are chained together in a cascade. One can think of a stage and its natural direction as the specification of how to wire the stage into the chain. The following diagrams may help understand the paradigme. The first shows two stages chained each with a Direction.FORWARD direction.

           FORWARD         FORWARD
       +------+       +-------+
       |      |       |       |
       |  +--in --+   |   +--in --+
    ---+  | Stage |   |   | Stage |  +---
          +--out--+   |   +--out--+  |
              |       |       |      |
              +-------+       +------+
 

The second diagram shows two stages, one in a Direction.FORWARD direction, while the other is wired in a Direction.REVERSED direction.

           FORWARD         REVERSED
       +------+               +------+
       |      |               |      |
       |  +--in --+       +--in --+  |
    ---+  | Stage |       | Stage |  +---
          +--out--+       +--out--+
              |               |
              +---------------+
 
Version:
$Revision: 1.7 $
See Also:
ModeStage, CascadeStage

Field Summary

static String
DIRECTION
protected Direction
forward
protected Direction
wired

Constructor Summary

Stage(Direction forwardDirection)

Method Summary

abstract Set
blockSizes()
Returns the Set of supported block sizes for this Stage.
abstract int
currentBlockSize()
Returns the currently set block size for the stage.
static Stage
getInstance(Cascade cascade, Direction forwardDirection)
static Stage
getInstance(IMode mode, Direction forwardDirection)
void
init(Map attributes)
Initialises the stage for operation with specific characteristics.
(package private) abstract void
initDelegate(Map attributes)
void
reset()
Resets the stage for re-initialisation and use with other characteristics.
(package private) abstract void
resetDelegate()
abstract 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.
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).
(package private) abstract void
updateDelegate(byte[] in, int inOffset, byte[] out, int outOffset)

Field Details

DIRECTION

public static final String DIRECTION

forward

protected Direction forward

wired

protected Direction wired

Constructor Details

Stage

protected Stage(Direction forwardDirection)

Method Details

blockSizes

public abstract Set blockSizes()
Returns the Set of supported block sizes for this Stage. Each element in the returned Set is an instance of Integer.
Returns:
a Set of supported block sizes.

currentBlockSize

public abstract int currentBlockSize()
            throws IllegalStateException
Returns the currently set block size for the stage.
Returns:
the current block size for this stage.

getInstance

public static final Stage getInstance(Cascade cascade,
                                      Direction forwardDirection)

getInstance

public static final Stage getInstance(IMode mode,
                                      Direction forwardDirection)

init

public void init(Map attributes)
            throws InvalidKeyException
Initialises the stage for operation with specific characteristics.
Parameters:
attributes - a set of name-value pairs that describes the desired future behaviour of this instance.

initDelegate

(package private)  abstract void initDelegate(Map attributes)
            throws InvalidKeyException

reset

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

resetDelegate

(package private)  abstract void resetDelegate()

selfTest

public abstract 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.

update

public void update(byte[] in,
                   int inOffset,
                   byte[] out,
                   int outOffset)
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.

updateDelegate

(package private)  abstract void updateDelegate(byte[] in,
                                                int inOffset,
                                                byte[] out,
                                                int outOffset)

Copyright © 2001, 2002, 2003 Free Software Foundation, Inc. All Rights Reserved.