gnu.crypto.assembly
Class Transformer
public abstract class Transformer
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:
- It can be chained to other instances, to form an
Assembly
. - When configured in an
Assembly
, it can be set to apply its
internal transformation on the input data stream before (pre-processing)
or after (post-processing) passing the input data to the next element in
the chain. Note that the same type Transformer
can be used as
either in pre-processing or a post-processing modes. - A special transformer --
LoopbackTransformer
-- is used to
close the chain. - A useful type of
Transformer
--one we're interested in--
has internal buffers. The distinction between a casual push (update)
operation and the last one allows to correctly flush any intermediate
bytes that may exist in those buffers.
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.
int | currentBlockSize() - Returns the block-size of this
Transformer .
|
(package private) abstract 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) abstract 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) abstract byte[] | lastUpdateDelegate()
|
void | reset() - Resets the
Transformer for re-initialisation and use with
other characteristics.
|
(package private) abstract 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) abstract byte[] | updateDelegate(byte[] in, int off, int len)
|
DIRECTION
public static final String DIRECTION
inBuffer
protected ByteArrayOutputStream inBuffer
outBuffer
protected ByteArrayOutputStream outBuffer
Transformer
protected Transformer()
Trivial protected constructor.
currentBlockSize
public int currentBlockSize()
Returns the block-size of this Transformer
. A value of
1
indicates that this instance is block-agnostic.
- the current minimal required block size.
delegateBlockSize
(package private) abstract 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.
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 TransformerException
isPostProcessing
public boolean isPostProcessing()
Returns true
if this Transformer
was wired in
post-processing mode; false
otherwise.
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.
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.
- the result of transformation.
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.
- the result of transformation.
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.
in
- the input data bytes.
- the result of transformation.
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
.
in
- the input data bytes.offset
- index of in
from which to start considering
data.length
- the count of bytes to process.
- the result of transformation.
lastUpdateDelegate
(package private) abstract 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) abstract void resetDelegate()
setMode
public void setMode(Operation mode)
Sets the operational mode of this Transformer
.
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.
- the result of transformation.
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.
in
- the input data bytes.
- the result of transformation.
update
public byte[] update(byte[] in,
int offset,
int length)
throws TransformerException
Processes a designated number of bytes from a given byte array.
in
- the input data bytes.offset
- index of in
from which to start considering
data.length
- the count of bytes to process.
- the result of transformation.
updateDelegate
(package private) abstract byte[] updateDelegate(byte[] in,
int off,
int len)
throws TransformerException
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Free Software Foundation,
Inc. All Rights Reserved.