gnu.crypto.assembly

Class Transformer

Known Direct Subclasses:
CascadeTransformer, DeflateTransformer, LoopbackTransformer, PaddingTransformer

public abstract class Transformer
extends java.lang.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.

Version:
$Revision: 1.2 $

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.
(package private) int
delegateBlockSize()
static Transformer
getCascadeTransformer(Cascade cascade)
static Transformer
getDeflateTransformer()
static Transformer
getPaddingTransformer(IPad padding)
void
init(Map attributes)
Initialises the Transformer for operation with specific characteristics.
(package private) void
initDelegate(Map attributes)
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.
(package private) byte[]
lastUpdateDelegate()
void
reset()
Resets the Transformer for re-initialisation and use with other characteristics.
(package private) void
resetDelegate()
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.
(package private) byte[]
updateDelegate(byte[] in, int off, int len)

Field Details

DIRECTION

public static final String 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.


delegateBlockSize

(package private)  int delegateBlockSize()


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 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.


initDelegate

(package private)  void initDelegate(Map attributes)
            throws TransformerException


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.


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.


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:
TransformerException - if a transformation-related exception occurs during the operation.

See Also:
lastUpdate(byte[],int,int)


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:
TransformerException - if a transformation-related exception occurs during the operation.

See Also:
lastUpdate(byte[],int,int)


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:
TransformerException - if a transformation-related exception occurs during the operation.

See Also:
lastUpdate(byte[],int,int)


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:
TransformerException - if a transformation-related exception occurs during the operation.


lastUpdateDelegate

(package private)  byte[] lastUpdateDelegate()
            throws TransformerException


reset

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


resetDelegate

(package private)  void resetDelegate()


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.


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:
TransformerException - if a transformation-related exception occurs during the operation.

See Also:
update(byte[],int,int)


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:
TransformerException - if a transformation-related exception occurs during the operation.

See Also:
update(byte[],int,int)


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:
TransformerException - if a transformation-related exception occurs during the operation.


updateDelegate

(package private)  byte[] updateDelegate(byte[] in,
                                         int off,
                                         int len)
            throws TransformerException


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