src/authAlgo.cpp

   1 /*
   2  *  anytun
   3  *
   4  *  The secure anycast tunneling protocol (satp) defines a protocol used
   5  *  for communication between any combination of unicast and anycast
   6  *  tunnel endpoints.  It has less protocol overhead than IPSec in Tunnel
   7  *  mode and allows tunneling of every ETHER TYPE protocol (e.g.
   8  *  ethernet, ip, arp ...). satp directly includes cryptography and
   9  *  message authentication based on the methodes used by SRTP.  It is
  10  *  intended to deliver a generic, scaleable and secure solution for
  11  *  tunneling and relaying of packets of any protocol.
  12  *
  13  *
  14  *  Copyright (C) 2007-2008 Othmar Gsenger, Erwin Nindl,
  15  *                          Christian Pointner <satp@wirdorange.org>
  16  *
  17  *  This file is part of Anytun.
  18  *
  19  *  Anytun is free software: you can redistribute it and/or modify
  20  *  it under the terms of the GNU General Public License version 3 as
  21  *  published by the Free Software Foundation.
  22  *
  23  *  Anytun is distributed in the hope that it will be useful,
  24  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  25  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  26  *  GNU General Public License for more details.
  27  *
  28  *  You should have received a copy of the GNU General Public License
  29  *  along with anytun.  If not, see <http://www.gnu.org/licenses/>.
  30  */
  31
  32 #include "authAlgo.h"
  33 #include "log.h"
  34 #include "buffer.h"
  35 #include "encryptedPacket.h"
  36
  37 #include <iostream>
  38 #include <cstring>
  39
  40 //****** NullAuthAlgo ******
  41 void NullAuthAlgo::generate(KeyDerivation& kd, EncryptedPacket& packet)
  42 {
  43 }
  44
  45 bool NullAuthAlgo::checkTag(KeyDerivation& kd, EncryptedPacket& packet)
  46 {
  47   return true;
  48 }
  49
  50 #ifndef NOCRYPT
  51 //****** Sha1AuthAlgo ******
  52
  53 Sha1AuthAlgo::Sha1AuthAlgo(kd_dir_t d) : AuthAlgo(d), key_(DIGEST_LENGTH)
  54 {
  55 #ifndef USE_SSL_CRYPTO
  56   gcry_error_t err = gcry_md_open(&handle_, GCRY_MD_SHA1, GCRY_MD_FLAG_HMAC);
  57   if(err) {
  58     cLog.msg(Log::PRIO_CRIT) << "Sha1AuthAlgo::Sha1AuthAlgo: Failed to open message digest algo";
  59     return;
  60   }
  61 #else
  62   HMAC_CTX_init(&ctx_);
  63   HMAC_Init_ex(&ctx_, NULL, 0, EVP_sha1(), NULL);
  64 #endif
  65 }
  66
  67 Sha1AuthAlgo::~Sha1AuthAlgo()
  68 {
  69 #ifndef USE_SSL_CRYPTO
  70   if(handle_)
  71     gcry_md_close(handle_);
  72 #else
  73   HMAC_CTX_cleanup(&ctx_);
  74 #endif
  75 }
  76
  77 void Sha1AuthAlgo::generate(KeyDerivation& kd, EncryptedPacket& packet)
  78 {
  79 #ifndef USE_SSL_CRYPTO
  80   if(!handle_)
  81     return;
  82 #endif
  83
  84   packet.addAuthTag();
  85   if(!packet.getAuthTagLength())
  86     return;
  87
  88   kd.generate(dir_, LABEL_SATP_MSG_AUTH, packet.getSeqNr(), key_);
  89 #ifndef USE_SSL_CRYPTO
  90   gcry_error_t err = gcry_md_setkey(handle_, key_.getBuf(), key_.getLength());
  91   if(err) {
  92     cLog.msg(Log::PRIO_ERR) << "Sha1AuthAlgo::setKey: Failed to set hmac key: " << LogGpgError(err);
  93     return;
  94   }
  95
  96   gcry_md_reset(handle_);
  97   gcry_md_write(handle_, packet.getAuthenticatedPortion(), packet.getAuthenticatedPortionLength());
  98   gcry_md_final(handle_);
  99   u_int8_t* hmac = gcry_md_read(handle_, 0);
 100 #else
 101   HMAC_Init_ex(&ctx_, key_.getBuf(), key_.getLength(), EVP_sha1(), NULL);
 102
 103   u_int8_t hmac[DIGEST_LENGTH];
 104   HMAC_Update(&ctx_, packet.getAuthenticatedPortion(), packet.getAuthenticatedPortionLength());
 105   HMAC_Final(&ctx_, hmac, NULL);
 106 #endif
 107
 108   u_int8_t* tag = packet.getAuthTag();
 109   u_int32_t length = (packet.getAuthTagLength() < DIGEST_LENGTH) ? packet.getAuthTagLength() : DIGEST_LENGTH;
 110
 111   if(length > DIGEST_LENGTH)
 112     std::memset(tag, 0, packet.getAuthTagLength());
 113
 114   std::memcpy(&tag[packet.getAuthTagLength() - length], &hmac[DIGEST_LENGTH - length], length);
 115 }
 116
 117 bool Sha1AuthAlgo::checkTag(KeyDerivation& kd, EncryptedPacket& packet)
 118 {
 119 #ifndef USE_SSL_CRYPTO
 120   if(!handle_)
 121     return false;
 122 #endif
 123
 124   packet.withAuthTag(true);
 125   if(!packet.getAuthTagLength())
 126     return true;
 127
 128   kd.generate(dir_, LABEL_SATP_MSG_AUTH, packet.getSeqNr(), key_);
 129 #ifndef USE_SSL_CRYPTO
 130   gcry_error_t err = gcry_md_setkey(handle_, key_.getBuf(), key_.getLength());
 131   if(err) {
 132     cLog.msg(Log::PRIO_ERR) << "Sha1AuthAlgo::setKey: Failed to set hmac key: " << LogGpgError(err);
 133     return false;
 134   }
 135
 136   gcry_md_reset(handle_);
 137   gcry_md_write(handle_, packet.getAuthenticatedPortion(), packet.getAuthenticatedPortionLength());
 138   gcry_md_final(handle_);
 139   u_int8_t* hmac = gcry_md_read(handle_, 0);
 140 #else
 141   HMAC_Init_ex(&ctx_, key_.getBuf(), key_.getLength(), EVP_sha1(), NULL);
 142
 143   u_int8_t hmac[DIGEST_LENGTH];
 144   HMAC_Update(&ctx_, packet.getAuthenticatedPortion(), packet.getAuthenticatedPortionLength());
 145   HMAC_Final(&ctx_, hmac, NULL);
 146 #endif
 147
 148   u_int8_t* tag = packet.getAuthTag();
 149   u_int32_t length = (packet.getAuthTagLength() < DIGEST_LENGTH) ? packet.getAuthTagLength() : DIGEST_LENGTH;
 150
 151   if(length > DIGEST_LENGTH)
 152     for(u_int32_t i=0; i < (packet.getAuthTagLength() - DIGEST_LENGTH); ++i)
 153       if(tag[i]) return false;
 154
 155   int ret = std::memcmp(&tag[packet.getAuthTagLength() - length], &hmac[DIGEST_LENGTH - length], length);
 156   packet.removeAuthTag();
 157
 158   if(ret)
 159     return false;
 160
 161   return true;
 162
 163 }
 164
 165 #endif
 166