gnu.javax.crypto.pad

Class BasePad

Implemented Interfaces:
IPad
Known Direct Subclasses:
ISO10126, PKCS1_V1_5, PKCS7, SSL3, TBC, TLS1

public abstract class BasePad
extends Object
implements IPad

An abstract class to facilitate implementing padding algorithms.

Field Summary

protected int
blockSize
The block size, in bytes, for this instance.
protected String
name
The canonical name prefix of the padding algorithm.

Fields inherited from interface gnu.javax.crypto.pad.IPad

PADDING_BLOCK_SIZE

Constructor Summary

BasePad(String name)
Trivial constructor for use by concrete subclasses.

Method Summary

void
init(int bs)
void
init(Map<K,V> attributes)
Initialises the algorithm with designated attributes.
String
name()
abstract byte[]
pad(byte[] in, int off, int len)
void
reset()
boolean
selfTest()
A default implementation of a correctness test that exercises the padder implementation, using block sizes varying from 2 to 256 bytes.
abstract void
setup()
If any additional checks or resource setup must be done by the subclass, then this is the hook for it.
protected boolean
test1BlockSize(int size, byte[] buffer)
The basic symmetric test for a padder given a specific block size.
abstract int
unpad(byte[] in, int off, int len)

Methods inherited from class java.lang.Object

clone, equals, extends Object> getClass, finalize, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Details

blockSize

protected int blockSize
The block size, in bytes, for this instance.

name

protected String name
The canonical name prefix of the padding algorithm.

Constructor Details

BasePad

protected BasePad(String name)
Trivial constructor for use by concrete subclasses.

Method Details

init

public void init(int bs)
            throws IllegalStateException
Specified by:
init in interface IPad

init

public void init(Map<K,V> attributes)
            throws IllegalStateException
Initialises the algorithm with designated attributes. Names, valid and/or recognisable by all concrete implementations are described in IPad class documentation. Other algorithm-specific attributes MUST be documented in the implementation class of that padding algorithm.

For compatibility reasons, this method is not declared abstract. Furthermore, and unless overridden, the default implementation will throw an UnsupportedOperationException. Concrete padding algorithms MUST override this method if they wish to offer an initialisation method that allows for other than the padding block size parameter to be specified.

Specified by:
init in interface IPad
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.
IllegalArgumentException - if the block size value is invalid.

name

public String name()
Specified by:
name in interface IPad

pad

public abstract byte[] pad(byte[] in,
                           int off,
                           int len)
Specified by:
pad in interface IPad

reset

public void reset()
Specified by:
reset in interface IPad

selfTest

public boolean selfTest()
A default implementation of a correctness test that exercises the padder implementation, using block sizes varying from 2 to 256 bytes.
Specified by:
selfTest in interface IPad
Returns:
true if the concrete implementation correctly unpads what it pads for all tested block sizes. Returns false if the test fails for any block size.

setup

public abstract void setup()
If any additional checks or resource setup must be done by the subclass, then this is the hook for it. This method will be called before the init(int) method returns.

test1BlockSize

protected boolean test1BlockSize(int size,
                                 byte[] buffer)
The basic symmetric test for a padder given a specific block size.

The code ensures that the implementation is capable of unpadding what it pads.

Parameters:
size - the block size to test.
buffer - a work buffer. It is exposed as an argument for this method to reduce un-necessary object allocations.
Returns:
true if the test passes; false otherwise.

unpad

public abstract int unpad(byte[] in,
                          int off,
                          int len)
            throws WrongPaddingException
Specified by:
unpad in interface IPad

BasePad.java -- Copyright (C) 2001, 2002, 2003, 2006, 2010 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.