cryptix.provider.padding
Class PKCS5
- Padding, Parameterized
A class for padding cipher data according to the following scheme,
described in section 6.2 of RSA Data Security, Inc.'s PKCS #5
standard:
...
An IllegalBlockSizeException is thrown (by the Cipher class) if
the block size is not 8 bytes.
References:
- PKCS#5: ... An RSA
Laboratories Technical Note;
Version 1.5; Revised November 1, 1993.
Copyright © 1997
Systemics Ltd on behalf of the
Cryptix Development Team.
All rights reserved.
$Revision: 1.7 $
- Raif S. Naffah
- David Hopwood
- Cryptix 2.2.2
PKCS5() - Creates a PKCS5 object.
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protected boolean | engineIsValidBlockSize(int size) - SPI: Returns true if size is a valid block size (in
bytes) for this algorithm.
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protected int | enginePad(byte[] in, int offset, int length) - Pads a given array of bytes.
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protected int | engineUnpad(byte[] in, int offset, int length) - Given the specified subarray of bytes that includes padding bytes, returns
the index indicating where padding starts.
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clone , engineGetParameter , engineIsValidBlockSize , enginePad , engineSetBlockSize , engineSetParameter , engineUnpad , getAlgorithm , getAlgorithms , getAlgorithms , getBlockSize , getInstance , getInstance , getParameter , pad , padLength , paddingScheme , setParameter , toString , unpad |
PKCS5
public PKCS5()
Creates a PKCS5 object.
engineIsValidBlockSize
protected boolean engineIsValidBlockSize(int size)
SPI: Returns true if
size is a valid block size (in
bytes) for this algorithm.
For PKCS#5 padding, the only valid
size is 8 bytes.
- engineIsValidBlockSize in interface PaddingScheme
enginePad
protected int enginePad(byte[] in,
int offset,
int length)
Pads a given array of bytes. The padding is written to the same buffer
that is used for input (in). When this method returns, the padded
block will be stored at in[offset+length..offset+7]
.
- enginePad in interface PaddingScheme
in
- the buffer containing the incomplete block.offset
- the offset into the in
buffer of the
first byte in the group of bytes to be padded.length
- the number of bytes from the in
buffer,
starting at offset
, that need to be padded.
engineUnpad
protected int engineUnpad(byte[] in,
int offset,
int length)
Given the specified subarray of bytes that includes padding bytes, returns
the index indicating where padding starts.
For PKCS#5, the padding bytes all have value
8 - (length % 8)
. Hence to find the number
of added bytes, it's enough to consider the last byte value of the
padded message.
- engineUnpad in interface PaddingScheme
in
- the buffer containing the bytes.offset
- the offset into the in buffer of the
first byte in the block.length
- the length of the block in bytes.
- the index into the in buffer indicating
where the padding starts.