/* ==================================================================== Licensed to the Apache Software Foundation (ASF) under one or more contributor license agreements. See the NOTICE file distributed with this work for Additional information regarding copyright ownership. The ASF licenses this file to You under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0 Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License. ==================================================================== */ namespace HH.WMS.Utils.NPOI.HSSF.Record.Crypto { using System; using System.Text; using HH.WMS.Utils.NPOI.Util; /** * Simple implementation of the alleged RC4 algorithm. * * Inspired by wikipedia's RC4 article * * @author Josh Micich */ internal class RC4 { private int _i, _j; private byte[] _s = new byte[256]; public RC4(byte[] key) { int key_length = key.Length; for (int i = 0; i < 256; i++) _s[i] = (byte)i; for (int i = 0, j = 0; i < 256; i++) { byte temp; j = (j + key[i % key_length] + _s[i]) & 255; temp = _s[i]; _s[i] = _s[j]; _s[j] = temp; } _i = 0; _j = 0; } public byte Output() { byte temp; _i = (_i + 1) & 255; _j = (_j + _s[_i]) & 255; temp = _s[_i]; _s[_i] = _s[_j]; _s[_j] = temp; return _s[(_s[_i] + _s[_j]) & 255]; } public void Encrypt(byte[] in1) { for (int i = 0; i < in1.Length; i++) { in1[i] = (byte)(in1[i] ^ Output()); } } public void Encrypt(byte[] in1, int OffSet, int len) { int end = OffSet + len; for (int i = OffSet; i < end; i++) { in1[i] = (byte)(in1[i] ^ Output()); } } public override String ToString() { StringBuilder sb = new StringBuilder(); sb.Append(GetType().Name).Append(" ["); sb.Append("i=").Append(_i); sb.Append(" j=").Append(_j); sb.Append("]"); sb.Append("\n"); sb.Append(HexDump.Dump(_s, 0, 0)); return sb.ToString(); } } }