org.gudy.bouncycastle.crypto.paddings
Interface BlockCipherPadding

All Known Implementing Classes:

PKCS7Padding

public interface BlockCipherPadding

Block cipher padders are expected to conform to this interface

Method Summary

int	addPadding(byte[] in, int inOff) add the pad bytes to the passed in block, returning the number of bytes added.
String	getPaddingName() Return the name of the algorithm the cipher implements.
void	init(SecureRandom random) Initialise the padder.
int	padCount(byte[] in) return the number of pad bytes present in the block.

Method Detail

init

void init(SecureRandom random)
          throws IllegalArgumentException

Initialise the padder.

Parameters:

random - the source of randomness for the padding, if required.

Throws:

IllegalArgumentException

getPaddingName

String getPaddingName()

Return the name of the algorithm the cipher implements.

Returns:

the name of the algorithm the cipher implements.

addPadding

int addPadding(byte[] in,
               int inOff)

add the pad bytes to the passed in block, returning the number of bytes added.

Note: this assumes that the last block of plain text is always passed to it inside in. i.e. if inOff is zero, indicating the entire block is to be overwritten with padding the value of in should be the same as the last block of plain text. The reason for this is that some modes such as "trailing bit compliment" base the padding on the last byte of plain text.

padCount

int padCount(byte[] in)
             throws InvalidCipherTextException

return the number of pad bytes present in the block.

Throws:

InvalidCipherTextException - if the padding is badly formed or invalid.