gnu.javax.crypto.assembly

Class Transformer


public abstract class Transformer
extends Object

A Transformer is an abstract representation of a two-way transformation that can be chained together with other instances of this type. Examples of such transformations in this library are: Cascade cipher, IPad algorithm, and a ZLib-based deflater/inflater algorithm. A special implementation of a Transformer to close a chain is also provided.

A Transformer is characterised by the followings:

To allow wiring Transformer instances together, a minimal-output-size in bytes is necessary. The trivial case of a value of 1 for such attribute practically means that no output buffering, from the previous element, is needed --which is independant of buffering the input if the Transformer implementation itself is block-based.

See Also:
CascadeTransformer, PaddingTransformer, DeflateTransformer

Field Summary

static String
DIRECTION
protected ByteArrayOutputStream
inBuffer
protected Operation
mode
protected ByteArrayOutputStream
outBuffer
protected Transformer
tail
protected Direction
wired

Constructor Summary

Transformer()
Trivial protected constructor.

Method Summary

int
currentBlockSize()
Returns the block-size of this Transformer.
static Transformer
getCascadeTransformer(Cascade cascade)
static Transformer
getDeflateTransformer()
static Transformer
getPaddingTransformer(IPad padding)
void
init(Map<K,V> attributes)
Initialises the Transformer for operation with specific characteristics.
boolean
isPostProcessing()
Returns true if this Transformer was wired in post-processing mode; false otherwise.
boolean
isPreProcessing()
Returns true if this Transformer was wired in pre-processing mode; false otherwise.
byte[]
lastUpdate()
Convenience method that calls the same method with three arguments.
byte[]
lastUpdate(byte b)
Convenience method that calls the method with same name and three arguments, using a byte array of length 1 whose contents are the designated byte.
byte[]
lastUpdate(byte[] in)
Convenience method that calls the same method with three arguments.
byte[]
lastUpdate(byte[] in, int offset, int length)
Processes a designated number of bytes from a given byte array and signals, at the same time, that this is the last push operation on this Transformer.
void
reset()
Resets the Transformer for re-initialisation and use with other characteristics.
void
setMode(Operation mode)
Sets the operational mode of this Transformer.
byte[]
update(byte b)
Convenience method that calls the method with same name and three arguments, using a byte array of length 1 whose contents are the designated byte.
byte[]
update(byte[] in)
Convenience method that calls the same method with three arguments.
byte[]
update(byte[] in, int offset, int length)
Processes a designated number of bytes from a given byte array.

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.transformer.direction"

inBuffer

protected ByteArrayOutputStream inBuffer

mode

protected Operation mode

outBuffer

protected ByteArrayOutputStream outBuffer

tail

protected Transformer tail

wired

protected Direction wired

Constructor Details

Transformer

protected Transformer()
Trivial protected constructor.

Method Details

currentBlockSize

public int currentBlockSize()
Returns the block-size of this Transformer. A value of 1 indicates that this instance is block-agnostic.
Returns:
the current minimal required block size.

getCascadeTransformer

public static final Transformer getCascadeTransformer(Cascade cascade)

getDeflateTransformer

public static final Transformer getDeflateTransformer()

getPaddingTransformer

public static final Transformer getPaddingTransformer(IPad padding)

init

public void init(Map<K,V> attributes)
            throws TransformerException
Initialises the Transformer 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 instance is already initialised.

isPostProcessing

public boolean isPostProcessing()
Returns true if this Transformer was wired in post-processing mode; false otherwise.
Returns:
true if this Transformer has been wired in post-processing mode; false otherwise.
Throws:
IllegalStateException - if this instance has not yet been assigned an operational type.

isPreProcessing

public boolean isPreProcessing()
Returns true if this Transformer was wired in pre-processing mode; false otherwise.
Returns:
true if this Transformer has been wired in pre-processing mode; false otherwise.
Throws:
IllegalStateException - if this instance has not yet been assigned an operational type.

lastUpdate

public byte[] lastUpdate()
            throws TransformerException
Convenience method that calls the same method with three arguments. A zero-long byte array is used.
Returns:
the result of transformation.
Throws:
IllegalStateException - if the instance is not initialised.
TransformerException - if a transformation-related exception occurs during the operation.

lastUpdate

public byte[] lastUpdate(byte b)
            throws TransformerException
Convenience method that calls the method with same name and three arguments, using a byte array of length 1 whose contents are the designated byte.
Parameters:
b - the byte to process.
Returns:
the result of transformation.
Throws:
IllegalStateException - if the instance is not initialised.
TransformerException - if a transformation-related exception occurs during the operation.

lastUpdate

public byte[] lastUpdate(byte[] in)
            throws TransformerException
Convenience method that calls the same method with three arguments. All bytes in in, starting from index position 0 are considered.
Parameters:
in - the input data bytes.
Returns:
the result of transformation.
Throws:
IllegalStateException - if the instance is not initialised.
TransformerException - if a transformation-related exception occurs during the operation.

lastUpdate

public byte[] lastUpdate(byte[] in,
                         int offset,
                         int length)
            throws TransformerException
Processes a designated number of bytes from a given byte array and signals, at the same time, that this is the last push operation on this Transformer.
Parameters:
in - the input data bytes.
offset - index of in from which to start considering data.
length - the count of bytes to process.
Returns:
the result of transformation.
Throws:
IllegalStateException - if the instance is not initialised.
TransformerException - if a transformation-related exception occurs during the operation.

reset

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

setMode

public void setMode(Operation mode)
Sets the operational mode of this Transformer.
Parameters:
mode - the processing mode this Transformer is required to operate in.
Throws:
IllegalStateException - if this instance has already been assigned an operational mode.

update

public byte[] update(byte b)
            throws TransformerException
Convenience method that calls the method with same name and three arguments, using a byte array of length 1 whose contents are the designated byte.
Parameters:
b - the byte to process.
Returns:
the result of transformation.
Throws:
IllegalStateException - if the instance is not initialised.
TransformerException - if a transformation-related exception occurs during the operation.

update

public byte[] update(byte[] in)
            throws TransformerException
Convenience method that calls the same method with three arguments. All bytes in in, starting from index position 0 are considered.
Parameters:
in - the input data bytes.
Returns:
the result of transformation.
Throws:
IllegalStateException - if the instance is not initialised.
TransformerException - if a transformation-related exception occurs during the operation.

update

public byte[] update(byte[] in,
                     int offset,
                     int length)
            throws TransformerException
Processes a designated number of bytes from a given byte array.
Parameters:
in - the input data bytes.
offset - index of in from which to start considering data.
length - the count of bytes to process.
Returns:
the result of transformation.
Throws:
IllegalStateException - if the instance is not initialised.
TransformerException - if a transformation-related exception occurs during the operation.

Transformer.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.