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gnu.javax.crypto.pad

Class PKCS1_V1_5

Implemented Interfaces:
IPad
public class PKCS1_V1_5
extends BasePad
A padding algorithm implementation of the EME-PKCS1-V1.5 encoding/decoding algorithm as described in section 7.2 of RFC-3447. This is effectively an Adapter over an instance of EME_PKCS1_V1_5 initialised with the RSA public shared modulus length (in bytes).

References:

  1. Public-Key Cryptography Standards (PKCS) #1:
    RSA Cryptography Specifications Version 2.1.
    Jakob Jonsson and Burt Kaliski.
See Also:
EME_PKCS1_V1_5

Field Summary

Fields inherited from class gnu.javax.crypto.pad.BasePad

blockSize, name

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

PADDING_BLOCK_SIZE

Method Summary

byte[]
pad(byte[] in, int offset, int length)
Returns the byte sequence that should be appended to the designated input.
boolean
selfTest()
A default implementation of a correctness test that exercises the padder implementation, using block sizes varying from 2 to 256 bytes.
void
setup()
If any additional checks or resource setup must be done by the subclass, then this is the hook for it.
int
unpad(byte[] in, int offset, int length)
Returns the number of bytes to discard from a designated input buffer.

Methods inherited from class gnu.javax.crypto.pad.BasePad

init, init, name, pad, reset, selfTest, setup, test1BlockSize, unpad

Methods inherited from class java.lang.Object

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

Method Details

pad

public byte[] pad(byte[] in,
                  int offset,
                  int length)
Returns the byte sequence that should be appended to the designated input.
Specified by:
pad in interface IPad
Overrides:
pad in interface BasePad
Parameters:
in - the input buffer containing the bytes to pad.
offset - the starting index of meaningful data in in.
length - the number of meaningful bytes in in.
Returns:
the possibly 0-byte long sequence to be appended to the designated input.

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
Overrides:
selfTest in interface BasePad
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 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 BasePad.init(int) method returns.
Overrides:
setup in interface BasePad

unpad

public int unpad(byte[] in,
                 int offset,
                 int length)
            throws WrongPaddingException
Returns the number of bytes to discard from a designated input buffer.
Specified by:
unpad in interface IPad
Overrides:
unpad in interface BasePad
Parameters:
in - the input buffer containing the bytes to unpad.
offset - the starting index of meaningful data in in.
length - the number of meaningful bytes in in.
Returns:
the number of bytes to discard, to the left of index position offset + length in in. In other words, if the return value of a successful invocation of this method is result, then the unpadded byte sequence will be offset + length - result bytes in in, starting from index position offset.
Throws:
WrongPaddingException - if the data is not terminated with the expected padding bytes.
PKCS1_V1_5.java -- Copyright (C) 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.

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