src/RC4Encrypt.cpp

   1 //
   2 // This file is part of the aMule Project.
   3 //
   4 // Copyright (c) 2003-2011 aMule Team ( admin@amule.org / http://www.amule.org )
   5 // Copyright (c) 2002-2011 Merkur ( devs@emule-project.net / http://www.emule-project.net )
   6 //
   7 // Any parts of this program derived from the xMule, lMule or eMule project,
   8 // or contributed by third-party developers are copyrighted by their
   9 // respective authors.
  10 //
  11 // This program is free software; you can redistribute it and/or modify
  12 // it under the terms of the GNU General Public License as published by
  13 // the Free Software Foundation; either version 2 of the License, or
  14 // (at your option) any later version.
  15 //
  16 // This program is distributed in the hope that it will be useful,
  17 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  18 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  19 // GNU General Public License for more details.
  20 //
  21 // You should have received a copy of the GNU General Public License
  22 // along with this program; if not, write to the Free Software
  23 // Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301, USA
  24 //
  25
  26
  27 #include "RC4Encrypt.h"
  28 #include <common/MD5Sum.h>
  29
  30
  31 #include <stdexcept>
  32
  33 CRC4EncryptableBuffer::CRC4EncryptableBuffer() : m_encrypted(false), m_hasKey(false), m_key()
  34 {
  35 }
  36
  37
  38 CRC4EncryptableBuffer::~CRC4EncryptableBuffer()
  39 {
  40 }
  41
  42 void CRC4EncryptableBuffer::Append(const uint8* buffer, int n)
  43 {
  44         wxASSERT(!m_encrypted);
  45         if (!m_encrypted) {
  46                 CMemFile::Append(buffer, n);
  47         } else {
  48                 throw std::runtime_error(
  49                         "(CRC4EncryptableBuffer::Append): "
  50                         "Tryed to append data to an encrypted buffer.");
  51         }
  52 }
  53
  54
  55 void CRC4EncryptableBuffer::Encrypt()
  56 {
  57         wxASSERT(!m_encrypted);
  58         RC4Crypt(GetRawBuffer(), GetRawBuffer(), GetLength());
  59         m_encrypted = true;
  60 }
  61
  62 void CRC4EncryptableBuffer::RC4Crypt( const uint8 *pachIn, uint8 *pachOut, uint32 nLen)
  63 {
  64         wxASSERT( m_hasKey && nLen > 0 );
  65
  66         if (m_hasKey) {
  67                 uint8 byX = m_key.byX;;
  68                 uint8 byY = m_key.byY;
  69                 uint8* pabyState = &m_key.abyState[0];;
  70
  71                 for (uint32 i = 0; i < nLen; ++i) {
  72                         uint8 byXorIndex;
  73                         byX = (byX + 1) % 256;
  74                         byY = (pabyState[byX] + byY) % 256;
  75                         std::swap(pabyState[byX], pabyState[byY]);
  76                         byXorIndex = (pabyState[byX] + pabyState[byY]) % 256;
  77
  78                         if (pachIn != NULL) {
  79                                 pachOut[i] = pachIn[i] ^ pabyState[byXorIndex];
  80                         }
  81                 }
  82
  83                 m_key.byX = byX;
  84                 m_key.byY = byY;
  85         } else {
  86                 throw std::runtime_error(
  87                         "(CRC4EncryptableBuffer::RC4Crypt): "
  88                         "Encrypt() has been called without a previous call"
  89                         "to SetKey().");
  90         }
  91 }
  92
  93 uint8 *CRC4EncryptableBuffer::Detach()
  94 {
  95         int n = GetLength();
  96         uint8 *ret = new uint8[n];
  97         memcpy(ret, GetRawBuffer(), n);
  98         ResetData();
  99         m_encrypted = false;
 100         return ret;
 101 }
 102
 103
 104 void CRC4EncryptableBuffer::SetKey(const MD5Sum& keyhash, bool bSkipDiscard)
 105 {
 106         wxASSERT(!m_hasKey);
 107         if (!m_hasKey) {
 108                 m_hasKey = true;
 109                 RC4CreateKey( keyhash.GetRawHash(), 16, bSkipDiscard);
 110         } else {
 111                 throw std::runtime_error( "(CRC4EncryptableBuffer::SetKey): SetKey() has been called twice.");
 112         }
 113 }
 114
 115
 116 void CRC4EncryptableBuffer::RC4CreateKey(const uint8* pachKeyData, uint32 nLen, bool bSkipDiscard)
 117 {
 118         uint8 index1;
 119         uint8 index2;
 120         uint8* pabyState;
 121
 122         pabyState= &m_key.abyState[0];
 123         for (int i = 0; i < 256; ++i) {
 124                 pabyState[i] = (uint8)i;
 125         }
 126
 127         m_key.byX = 0;
 128         m_key.byY = 0;
 129         index1 = 0;
 130         index2 = 0;
 131
 132         for (int i = 0; i < 256; ++i) {
 133                 index2 = (pachKeyData[index1] + pabyState[i] + index2) % 256;
 134                 std::swap(pabyState[i], pabyState[index2]);
 135                 index1 = (uint8)((index1 + 1) % nLen);
 136         }
 137
 138         if (!bSkipDiscard) {
 139                 RC4Crypt(NULL, NULL, 1024);
 140         }
 141 }
 142
 143 void CRC4EncryptableBuffer::ResetData()
 144 {
 145         m_encrypted = false;
 146         // Not touching the keys.
 147         CMemFile::ResetData();
 148 }
 149
 150 void CRC4EncryptableBuffer::FullReset()
 151 {
 152         ResetData();
 153         m_hasKey = false;
 154         memset(&m_key, 0, sizeof(RC4_Key_Struct));
 155 }