include/libtorrent/pe_crypto.hpp

   1 /*
   2
   3 Copyright (c) 2007, Un Shyam
   4 All rights reserved.
   5
   6 Redistribution and use in source and binary forms, with or without
   7 modification, are permitted provided that the following conditions
   8 are met:
   9
  10     * Redistributions of source code must retain the above copyright
  11       notice, this list of conditions and the following disclaimer.
  12     * Redistributions in binary form must reproduce the above copyright
  13       notice, this list of conditions and the following disclaimer in
  14       the documentation and/or other materials provided with the distribution.
  15     * Neither the name of the author nor the names of its
  16       contributors may be used to endorse or promote products derived
  17       from this software without specific prior written permission.
  18
  19 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
  20 AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  21 IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  22 ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
  23 LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  24 CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  25 SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  26 INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  27 CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  28 ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  29 POSSIBILITY OF SUCH DAMAGE.
  30
  31 */
  32
  33 #ifndef TORRENT_DISABLE_ENCRYPTION
  34
  35 #ifndef TORRENT_PE_CRYPTO_HPP_INCLUDED
  36 #define TORRENT_PE_CRYPTO_HPP_INCLUDED
  37
  38 #include <openssl/dh.h>
  39 #include <openssl/engine.h>
  40 #include <openssl/rc4.h>
  41
  42 #include "libtorrent/peer_id.hpp" // For sha1_hash
  43 #include "libtorrent/assert.hpp"
  44
  45 namespace libtorrent
  46 {
  47         class dh_key_exchange
  48         {
  49         public:
  50                 dh_key_exchange();
  51                 ~dh_key_exchange();
  52                 bool good() const { return m_dh; }
  53
  54                 // Get local public key, always 96 bytes
  55                 char const* get_local_key() const;
  56
  57                 // read remote_pubkey, generate and store shared secret in
  58                 // m_dh_secret.
  59                 int compute_secret(const char* remote_pubkey);
  60
  61                 char const* get_secret() const { return m_dh_secret; }
  62
  63                 sha1_hash const& get_hash_xor_mask() const { return m_xor_mask; }
  64
  65         private:
  66                 int get_local_key_size() const
  67                 {
  68                         TORRENT_ASSERT(m_dh);
  69                         return BN_num_bytes(m_dh->pub_key);
  70                 }
  71
  72                 DH* m_dh;
  73
  74                 char m_dh_local_key[96];
  75                 char m_dh_secret[96];
  76                 sha1_hash m_xor_mask;
  77         };
  78
  79         class RC4_handler // Non copyable
  80         {
  81         public:
  82                 // Input longkeys must be 20 bytes
  83                 RC4_handler(const sha1_hash& rc4_local_longkey,
  84                                          const sha1_hash& rc4_remote_longkey)
  85
  86                 {
  87                         RC4_set_key(&m_local_key, 20,
  88                                                  reinterpret_cast<unsigned char const*>(rc4_local_longkey.begin()));
  89                         RC4_set_key(&m_remote_key, 20,
  90                                                  reinterpret_cast<unsigned char const*>(rc4_remote_longkey.begin()));
  91
  92                         // Discard first 1024 bytes
  93                         char buf[1024];
  94                         encrypt(buf, 1024);
  95                         decrypt(buf, 1024);
  96                 };
  97
  98                 ~RC4_handler() {};
  99
 100                 void encrypt(char* pos, int len)
 101                 {
 102                         TORRENT_ASSERT(len >= 0);
 103                         TORRENT_ASSERT(pos);
 104
 105                         RC4 (&m_local_key, len, reinterpret_cast<unsigned char const*>(pos),
 106                                  reinterpret_cast<unsigned char*>(pos));
 107                 }
 108
 109                 void decrypt(char* pos, int len)
 110                 {
 111                         TORRENT_ASSERT(len >= 0);
 112                         TORRENT_ASSERT(pos);
 113
 114                         RC4 (&m_remote_key, len, reinterpret_cast<unsigned char const*>(pos),
 115                                  reinterpret_cast<unsigned char*>(pos));
 116                 }
 117
 118         private:
 119                 RC4_KEY m_local_key; // Key to encrypt outgoing data
 120                 RC4_KEY m_remote_key; // Key to decrypt incoming data
 121         };
 122
 123 } // namespace libtorrent
 124
 125 #endif // TORRENT_PE_CRYPTO_HPP_INCLUDED
 126 #endif // TORRENT_DISABLE_ENCRYPTION
 127