com.microej.crypto.internal.cipher.padding

Class PKCS5Padding

java.lang.Object

com.microej.crypto.internal.cipher.padding.PKCS5Padding

All Implemented Interfaces:

Padding

public final class PKCS5Padding
extends Object
implements Padding

This class implements padding as specified in the PKCS#5 standard.

Author:

Gigi Ankeny

See Also:

Padding

Constructor Summary

Constructors

Constructor and Description
PKCS5Padding(int blockSize)

Method Summary

Modifier and Type	Method and Description
int	padLength(int len) Determines how long the padding will be for a given input length.
void	padWithLen(byte[] in, int off, int len) Adds the given number of padding bytes to the data input.
int	unpad(byte[] in, int off, int len) Returns the index where the padding starts.

Methods inherited from class java.lang.Object

clone, equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

PKCS5Padding

public PKCS5Padding(int blockSize)

Method Detail

padLength

public int padLength(int len)

Determines how long the padding will be for a given input length.

Specified by:

padLength in interface Padding

Parameters:

len - the length of the data to pad

Returns:

the length of the padding

padWithLen

public void padWithLen(byte[] in,
                       int off,
                       int len)
                throws ShortBufferException

Adds the given number of padding bytes to the data input. The value of the padding bytes is determined by the specific padding mechanism that implements this interface.

Specified by:

padWithLen in interface Padding

Parameters:

in - the input buffer with the data to pad

off - the offset in in where the padding bytes are appended

len - the number of padding bytes to add

Throws:

ShortBufferException - if in is too small to hold the padding bytes

unpad

public int unpad(byte[] in,
                 int off,
                 int len)

Returns the index where the padding starts.

Given a buffer with padded data, this method returns the index where the padding starts.

Specified by:

unpad in interface Padding

Parameters:

in - the buffer with the padded data

off - the offset in in where the padded data starts

len - the length of the padded data

Returns:

the index where the padding starts, or -1 if the input is not properly padded