| /* |
| * Copyright (c) 2003, 2016, Oracle and/or its affiliates. All rights reserved. |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. Oracle designates this |
| * particular file as subject to the "Classpath" exception as provided |
| * by Oracle in the LICENSE file that accompanied this code. |
| * |
| * This code is distributed in the hope that it will be useful, but WITHOUT |
| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| */ |
| |
| 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 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. |
| * |
| * @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; |
| |
| if ((off + len) > 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[off + len - 1] = paddingOctet; |
| return; |
| } |
| |
| /** |
| * 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; |
| } |
| |
| byte lastByte = in[off + len - 1]; |
| int padValue = (int)lastByte & 0x0ff; |
| if ((padValue < 0x01) |
| || (padValue > blockSize)) { |
| return -1; |
| } |
| |
| int start = off + len - padValue; |
| if (start < off) { |
| return -1; |
| } |
| |
| return start; |
| } |
| |
| /** |
| * 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; |
| } |
| } |