mpi.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 anytun.org <satp@wirdorange.org>
  15  *
  16  *  This program is free software; you can redistribute it and/or modify
  17  *  it under the terms of the GNU General Public License version 2
  18  *  as published by the Free Software Foundation.
  19  *
  20  *  This program is distributed in the hope that it will be useful,
  21  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  22  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  23  *  GNU General Public License for more details.
  24  *
  25  *  You should have received a copy of the GNU General Public License
  26  *  along with this program (see the file COPYING included with this
  27  *  distribution); if not, write to the Free Software Foundation, Inc.,
  28  *  59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  29  */
  30
  31 #include "mpi.h"
  32
  33 #include "datatypes.h"
  34 #include "cipher.h"
  35
  36 #include <stdexcept>
  37 #include <gcrypt.h>
  38
  39 #include <iostream>
  40
  41 Mpi::Mpi() : val_(NULL)
  42 {
  43   val_ = gcry_mpi_set_ui(NULL, 0);
  44   if(!val_)
  45     throw std::bad_alloc();
  46 }
  47
  48 Mpi::Mpi(u_int8_t length) : val_(NULL)
  49 {
  50   val_ = gcry_mpi_new(length);
  51   if(!val_)
  52     throw std::bad_alloc();
  53 }
  54
  55 Mpi::Mpi(const Mpi &src) : val_(NULL)
  56 {
  57   val_ = gcry_mpi_copy(src.val_);
  58   if(!val_)
  59     throw std::bad_alloc();
  60 }
  61
  62 Mpi::Mpi(const u_int8_t* src, u_int32_t len) : val_(NULL)
  63 {
  64   u_int8_t* src_cpy = new u_int8_t[len+1];
  65   if(!src_cpy)
  66     throw std::bad_alloc();
  67
  68   u_int8_t* buf = src_cpy;
  69   u_int32_t buf_len = len;
  70   if(src[0] & 0x80) // this would be a negative number, scan can't handle this :(
  71   {
  72     src_cpy[0] = 0;
  73     buf++;
  74     buf_len++;
  75   }
  76   std::memcpy(buf, src, len);
  77
  78   gcry_mpi_scan( &val_, GCRYMPI_FMT_STD, src_cpy, buf_len, NULL );
  79   delete[] src_cpy;
  80   if(!val_)
  81     throw std::bad_alloc();
  82 }
  83
  84 Mpi::~Mpi()
  85 {
  86   gcry_mpi_release( val_ );
  87 }
  88
  89
  90 void Mpi::operator=(const Mpi &src)
  91 {
  92   gcry_mpi_release( val_ );
  93   val_ = gcry_mpi_copy(src.val_);
  94   if(!val_)
  95     throw std::bad_alloc();
  96 }
  97
  98 void Mpi::operator=(const u_int32_t src)
  99 {
 100   gcry_mpi_release( val_ );
 101   val_ = gcry_mpi_set_ui(NULL, src);
 102   if(!val_)
 103     throw std::bad_alloc();
 104 }
 105
 106 Mpi Mpi::operator+(const Mpi &b) const
 107 {
 108   Mpi res;
 109   gcry_mpi_add(res.val_, val_, b.val_);
 110   return res;
 111 }
 112
 113 Mpi Mpi::operator+(const u_int32_t &b) const
 114 {
 115   Mpi res;
 116   gcry_mpi_add_ui(res.val_, val_, b);
 117   return res;
 118 }
 119
 120 Mpi Mpi::operator*(const u_int32_t n) const
 121 {
 122   Mpi res;
 123   gcry_mpi_mul_ui(res.val_, val_, n);
 124   return res;
 125 }
 126
 127 Mpi Mpi::operator/(const Mpi &b) const
 128 {
 129   Mpi res;
 130   gcry_mpi_div(res.val_, NULL, val_, b.val_, 0);
 131   return res;
 132 }
 133
 134 //TODO: this is outstandingly ugly!!!!!!!!
 135 Mpi Mpi::operator^(const Mpi &b) const
 136 {
 137   u_int32_t a_len = gcry_mpi_get_nbits(val_);
 138   u_int32_t b_len = gcry_mpi_get_nbits(b.val_);
 139
 140   Mpi res = (a_len >= b_len) ? Mpi(*this) : Mpi(b);
 141
 142   for(u_int32_t i=0; i<a_len && i<b_len; i++) {
 143     if(gcry_mpi_test_bit(val_, i) ^ gcry_mpi_test_bit(b.val_, i))
 144       gcry_mpi_set_bit(res.val_, i);
 145     else
 146       gcry_mpi_clear_bit(res.val_, i);
 147   }
 148   return res;
 149 }
 150
 151 Mpi Mpi::mul2exp(u_int32_t e) const
 152 {
 153   Mpi res;
 154   gcry_mpi_mul_2exp( res.val_, val_, e );
 155   return res;
 156 }
 157
 158 //TODO: problem, seems as gcry_mpi_(a)print doesn't work for mpi values of '0'
 159 u_int8_t* Mpi::getNewBuf(u_int32_t* written) const
 160 {
 161   u_int8_t* res_cpy;
 162   gcry_mpi_aprint( GCRYMPI_FMT_STD, &res_cpy, written, val_ );
 163   if(!res_cpy)
 164     throw std::bad_alloc();
 165
 166   u_int8_t* buf = res_cpy;
 167   if(*written > 1 && ! (res_cpy[0])) // positive number with highestBit set
 168   {
 169     buf++;
 170     (*written)--;
 171   }
 172
 173   u_int8_t* res = new u_int8_t[*written];
 174   if(!res)
 175     throw std::bad_alloc();
 176
 177   std::memcpy(res, buf, *written);
 178
 179   gcry_free(res_cpy);
 180
 181   return res;
 182 }
 183
 184 //TODO: why does this not work ?????
 185 std::string Mpi::getHexDump() const
 186 {
 187 //   u_int8_t *buf;
 188 //   u_int32_t len;
 189 //   gcry_mpi_aprint( GCRYMPI_FMT_HEX, &buf, &len, val_ );
 190 //   std::string res(buf, len);
 191 //   delete[] buf;
 192
 193   gcry_mpi_dump( val_ );
 194   std::string res("\n");
 195   return res;
 196 }
 197
 198 u_int32_t Mpi::getLength() const
 199 {
 200   return gcry_mpi_get_nbits( val_ );
 201 }