package org.bouncycastle.crypto.paddings;import java.security.SecureRandom;import org.bouncycastle.crypto.InvalidCipherTextException;/** * A padder that adds X9.23 padding to a block - if a SecureRandom is * passed in random padding is assumed, otherwise padding with zeros is used. */public class X923Padding    implements BlockCipherPadding{    SecureRandom    random = null;    /**     * Initialise the padder.     *     * @param random a SecureRandom if one is available.     */    public void init(SecureRandom random)        throws IllegalArgumentException    {        this.random = random;    }    /**     * Return the name of the algorithm the padder implements.     *     * @return the name of the algorithm the padder implements.     */    public String getPaddingName()    {        return "X9.23";    }    /**     * add the pad bytes to the passed in block, returning the     * number of bytes added.     */    public int addPadding(        byte[]  in,        int     inOff)    {        byte code = (byte)(in.length - inOff);        while (inOff < in.length - 1)        {            if (random == null)            {                in[inOff] = 0;            }            else            {                in[inOff] = (byte)random.nextInt();            }            inOff++;        }        in[inOff] = code;        return code;    }    /**     * return the number of pad bytes present in the block.     */    public int padCount(byte[] in)        throws InvalidCipherTextException    {        int count = in[in.length - 1] & 0xff;        if (count > in.length)        {            throw new InvalidCipherTextException("pad block corrupted");        }        return count;    }}