001: /*
002: * $Id: ARCFOUREncryption.java 2699 2007-04-19 12:19:40Z blowagie $
003: *
004: * Copyright 2006 Paulo Soares
005: *
006: * The contents of this file are subject to the Mozilla Public License Version 1.1
007: * (the "License"); you may not use this file except in compliance with the License.
008: * You may obtain a copy of the License at http://www.mozilla.org/MPL/
009: *
010: * Software distributed under the License is distributed on an "AS IS" basis,
011: * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
012: * for the specific language governing rights and limitations under the License.
013: *
014: * The Original Code is 'iText, a free JAVA-PDF library'.
015: *
016: * The Initial Developer of the Original Code is Bruno Lowagie. Portions created by
017: * the Initial Developer are Copyright (C) 1999, 2000, 2001, 2002 by Bruno Lowagie.
018: * All Rights Reserved.
019: * Co-Developer of the code is Paulo Soares. Portions created by the Co-Developer
020: * are Copyright (C) 2000, 2001, 2002 by Paulo Soares. All Rights Reserved.
021: *
022: * Contributor(s): all the names of the contributors are added in the source code
023: * where applicable.
024: *
025: * Alternatively, the contents of this file may be used under the terms of the
026: * LGPL license (the "GNU LIBRARY GENERAL PUBLIC LICENSE"), in which case the
027: * provisions of LGPL are applicable instead of those above. If you wish to
028: * allow use of your version of this file only under the terms of the LGPL
029: * License and not to allow others to use your version of this file under
030: * the MPL, indicate your decision by deleting the provisions above and
031: * replace them with the notice and other provisions required by the LGPL.
032: * If you do not delete the provisions above, a recipient may use your version
033: * of this file under either the MPL or the GNU LIBRARY GENERAL PUBLIC LICENSE.
034: *
035: * This library is free software; you can redistribute it and/or modify it
036: * under the terms of the MPL as stated above or under the terms of the GNU
037: * Library General Public License as published by the Free Software Foundation;
038: * either version 2 of the License, or any later version.
039: *
040: * This library is distributed in the hope that it will be useful, but WITHOUT
041: * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
042: * FOR A PARTICULAR PURPOSE. See the GNU Library general Public License for more
043: * details.
044: *
045: * If you didn't download this code from the following link, you should check if
046: * you aren't using an obsolete version:
047: * http://www.lowagie.com/iText/
048: */
049: package com.lowagie.text.pdf.crypto;
050:
051: public class ARCFOUREncryption {
052: private byte state[] = new byte[256];
053: private int x;
054: private int y;
055:
056: /** Creates a new instance of ARCFOUREncryption */
057: public ARCFOUREncryption() {
058: }
059:
060: public void prepareARCFOURKey(byte key[]) {
061: prepareARCFOURKey(key, 0, key.length);
062: }
063:
064: public void prepareARCFOURKey(byte key[], int off, int len) {
065: int index1 = 0;
066: int index2 = 0;
067: for (int k = 0; k < 256; ++k)
068: state[k] = (byte) k;
069: x = 0;
070: y = 0;
071: byte tmp;
072: for (int k = 0; k < 256; ++k) {
073: index2 = (key[index1 + off] + state[k] + index2) & 255;
074: tmp = state[k];
075: state[k] = state[index2];
076: state[index2] = tmp;
077: index1 = (index1 + 1) % len;
078: }
079: }
080:
081: public void encryptARCFOUR(byte dataIn[], int off, int len,
082: byte dataOut[], int offOut) {
083: int length = len + off;
084: byte tmp;
085: for (int k = off; k < length; ++k) {
086: x = (x + 1) & 255;
087: y = (state[x] + y) & 255;
088: tmp = state[x];
089: state[x] = state[y];
090: state[y] = tmp;
091: dataOut[k - off + offOut] = (byte) (dataIn[k] ^ state[(state[x] + state[y]) & 255]);
092: }
093: }
094:
095: public void encryptARCFOUR(byte data[], int off, int len) {
096: encryptARCFOUR(data, off, len, data, off);
097: }
098:
099: public void encryptARCFOUR(byte dataIn[], byte dataOut[]) {
100: encryptARCFOUR(dataIn, 0, dataIn.length, dataOut, 0);
101: }
102:
103: public void encryptARCFOUR(byte data[]) {
104: encryptARCFOUR(data, 0, data.length, data, 0);
105: }
106: }
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