diff -r fd16c54261b3 -r 90ce3da70b43 jdk/src/share/classes/com/sun/crypto/provider/PKCS5Padding.java --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/jdk/src/share/classes/com/sun/crypto/provider/PKCS5Padding.java Sat Dec 01 00:00:00 2007 +0000 @@ -0,0 +1,128 @@ +/* + * Copyright 1997-2007 Sun Microsystems, Inc. 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. Sun designates this + * particular file as subject to the "Classpath" exception as provided + * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, + * CA 95054 USA or visit www.sun.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 PKCS#5 standard. + * + * @author Gigi Ankeny + * + * + * @see Padding + */ +final class PKCS5Padding implements Padding { + + private int blockSize; + + PKCS5Padding(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 in where the padding bytes + * are appended + * @param len the number of padding bytes to add + * + * @exception ShortBufferException if in 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); + for (int i = 0; i < len; i++) { + in[i + off] = paddingOctet; + } + return; + } + + /** + * Returns the index where the padding starts. + * + *

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 in 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 - ((int)lastByte & 0x0ff); + if (start < off) { + return -1; + } + + for (int i = 0; i < ((int)lastByte & 0x0ff); i++) { + if (in[start+i] != lastByte) { + 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; + } +}