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package com.sun.crypto.provider;

import javax.crypto.ShortBufferException;

This class implements padding as specified in the W3 XML ENC standard.
Author:Valerie Peng
See Also:
/** * This class implements padding as specified in the W3 XML ENC standard. * * @author Valerie Peng * * * @see Padding */
final class ISO10126Padding implements Padding { private int blockSize; ISO10126Padding(int blockSize) { this.blockSize = blockSize; }
Adds the given number of padding bytes to the data input. The value of the padding bytes is determined by the specific padding mechanism that implements this interface.
Params:
  • in – the input buffer with the data to pad
  • off – the offset in in where the padding bytes are appended
  • len – the number of padding bytes to add
Throws:
/** * Adds the given number of padding bytes to the data input. * The value of the padding bytes is determined * by the specific padding mechanism that implements this * interface. * * @param in the input buffer with the data to pad * @param off the offset in <code>in</code> where the padding bytes * are appended * @param len the number of padding bytes to add * * @exception ShortBufferException if <code>in</code> is too small to hold * the padding bytes */
public void padWithLen(byte[] in, int off, int len) throws ShortBufferException { if (in == null) return; int idx = Math.addExact(off, len); if (idx > in.length) { throw new ShortBufferException("Buffer too small to hold padding"); } byte paddingOctet = (byte) (len & 0xff); byte[] padding = new byte[len - 1]; SunJCE.getRandom().nextBytes(padding); System.arraycopy(padding, 0, in, off, len - 1); in[idx - 1] = paddingOctet; return; }
Returns the index where the padding starts.

Given a buffer with padded data, this method returns the index where the padding starts.

Params:
  • in – the buffer with the padded data
  • off – the offset in in where the padded data starts
  • len – the length of the padded data
Returns:the index where the padding starts, or -1 if the input is not properly padded
/** * Returns the index where the padding starts. * * <p>Given a buffer with padded data, this method returns the * index where the padding starts. * * @param in the buffer with the padded data * @param off the offset in <code>in</code> where the padded data starts * @param len the length of the padded data * * @return the index where the padding starts, or -1 if the input is * not properly padded */
public int unpad(byte[] in, int off, int len) { if ((in == null) || (len == 0)) { // this can happen if input is really a padded buffer return 0; } int idx = Math.addExact(off, len); byte lastByte = in[idx - 1]; int padValue = (int)lastByte & 0x0ff; if ((padValue < 0x01) || (padValue > blockSize)) { return -1; } int start = idx - padValue; if (start < off) { return -1; } return start; }
Determines how long the padding will be for a given input length.
Params:
  • len – the length of the data to pad
Returns:the length of the padding
/** * Determines how long the padding will be for a given input length. * * @param len the length of the data to pad * * @return the length of the padding */
public int padLength(int len) { int paddingOctet = blockSize - (len % blockSize); return paddingOctet; } }