package com.google.bitcoin.bouncycastle.crypto.paddings; import java.security.SecureRandom; import com.google.bitcoin.bouncycastle.crypto.InvalidCipherTextException; /** * A padder that adds NULL byte padding to a block. */ public class ZeroBytePadding implements BlockCipherPadding { /** * Initialise the padder. * * @param random - a SecureRandom if available. */ public void init(SecureRandom random) throws IllegalArgumentException { // nothing to do. } /** * Return the name of the algorithm the padder implements. * * @return the name of the algorithm the padder implements. */ public String getPaddingName() { return "ZeroByte"; } /** * add the pad bytes to the passed in block, returning the * number of bytes added. */ public int addPadding( byte[] in, int inOff) { int added = (in.length - inOff); while (inOff < in.length) { in[inOff] = (byte) 0; inOff++; } return added; } /** * return the number of pad bytes present in the block. */ public int padCount(byte[] in) throws InvalidCipherTextException { int count = in.length; while (count > 0) { if (in[count - 1] != 0) { break; } count--; } return in.length - count; } }