gnu.crypto.assembly
Class Stage

java.lang.Object
  gnu.crypto.assembly.Stage

Direct Known Subclasses:

CascadeStage, ModeStage

public abstract class Stage

extends java.lang.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: 1.2 $

See Also:

ModeStage, CascadeStage

Field Summary

static java.lang.String	DIRECTION
protected Direction	forward
protected Direction	wired

Constructor Summary

protected

Stage(Direction forwardDirection)

Method Summary

abstract java.util.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(java.util.Map attributes) Initialises the stage for operation with specific characteristics.
(package private) abstract void	initDelegate(java.util.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)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

DIRECTION

public static final java.lang.String DIRECTION

See Also:

Constant Field Values

forward

protected Direction forward

wired

protected Direction wired

Constructor Detail

Stage

protected Stage(Direction forwardDirection)

Method Detail

getInstance

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

getInstance

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

blockSizes

public abstract java.util.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.

init

public void init(java.util.Map attributes)
          throws java.security.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.

Throws:

java.lang.IllegalStateException - if the instance is already initialised.

java.security.InvalidKeyException - if the key data is invalid.

currentBlockSize

public abstract int currentBlockSize()
                              throws java.lang.IllegalStateException

Returns the currently set block size for the stage.

Returns:

the current block size for this stage.

Throws:

java.lang.IllegalStateException - if the instance is not initialised.

reset

public void reset()

Resets the stage for re-initialisation and use with other characteristics. This method always succeeds.

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:

java.lang.IllegalStateException - if the instance is not initialised.

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.

initDelegate

abstract void initDelegate(java.util.Map attributes)
                    throws java.security.InvalidKeyException

Throws:

java.security.InvalidKeyException

resetDelegate

abstract void resetDelegate()

updateDelegate

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