gnu.javax.crypto.assembly
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.
CascadeTransformer, PaddingTransformer, DeflateTransformer
int | currentBlockSize()- Returns the block-size of this
Transformer.
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static Transformer | getCascadeTransformer(Cascade cascade)
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static Transformer | getDeflateTransformer()
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static Transformer | getPaddingTransformer(IPad padding)
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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.
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byte[] | lastUpdate()- Convenience method that calls the same method with three arguments.
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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.
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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.
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void | reset()- Resets the
Transformer for re-initialisation and use with
other characteristics.
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void | setMode(Operation mode)- Sets the operational mode of this
Transformer.
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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.
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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.
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clone, equals, extends Object> getClass, finalize, hashCode, notify, notifyAll, toString, wait, wait, wait |
DIRECTION
public static final String DIRECTION
- "gnu.crypto.assembly.transformer.direction"
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.
init
public void init(Map<K,V> 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.
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.
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.
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.
Transformer.java --
Copyright (C) 2003, 2006 Free Software Foundation, Inc.
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it under the terms of the GNU General Public License as published by
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