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The Bouncy Castle Crypto package is a Java implementation of cryptographic algorithms. This jar contains JCE provider and lightweight API for the Bouncy Castle Cryptography APIs for JDK 1.4.

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package org.bouncycastle.crypto.paddings;

import java.security.SecureRandom;

import org.bouncycastle.crypto.InvalidCipherTextException;

/**
 * A padder that adds Trailing-Bit-Compliment padding to a block.
 * 

* This padding pads the block out with the compliment of the last bit * of the plain text. *

*/ public class TBCPadding 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 "TBC"; } /** * 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. *

*/ public int addPadding( byte[] in, int inOff) { int count = in.length - inOff; byte code; if (inOff > 0) { code = (byte)((in[inOff - 1] & 0x01) == 0 ? 0xff : 0x00); } else { code = (byte)((in[in.length - 1] & 0x01) == 0 ? 0xff : 0x00); } while (inOff < in.length) { in[inOff] = code; inOff++; } return count; } /** * return the number of pad bytes present in the block. */ public int padCount(byte[] in) throws InvalidCipherTextException { byte code = in[in.length - 1]; int index = in.length - 1; while (index > 0 && in[index - 1] == code) { index--; } return in.length - index; } }




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