package org.bouncycastle.crypto.paddings;
import java.security.SecureRandom;
import org.bouncycastle.crypto.InvalidCipherTextException;
/**
* Block cipher padders are expected to conform to this interface
*/
public interface BlockCipherPadding
{
/**
* Initialise the padder.
*
* @param random the source of randomness for the padding, if required.
*/
public void init(SecureRandom random)
throws IllegalArgumentException;
/**
* Return the name of the algorithm the cipher implements.
*
* @return the name of the algorithm the cipher implements.
*/
public String getPaddingName();
/**
* add the pad bytes to the passed in block, returning the
* number of bytes added.
* <p>
* 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.
* </p>
*/
public int addPadding(byte[] in, int inOff);
/**
* return the number of pad bytes present in the block.
* @exception InvalidCipherTextException if the padding is badly formed
* or invalid.
*/
public int padCount(byte[] in)
throws InvalidCipherTextException;
}