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 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 "authAlgo.h"
  32 #include "log.h"
  33 #include "buffer.h"
  34 #include "authTag.h"
  35 #include "threadUtils.hpp"
  36
  37 #include <gcrypt.h>
  38
  39 //****** NullAuthAlgo ******
  40
  41 AuthTag NullAuthAlgo::calc(const Buffer& buf)
  42 {
  43   return AuthTag(0);
  44 }
  45
  46 //****** Sha1AuthAlgo ******
  47
  48 Sha1AuthAlgo::Sha1AuthAlgo() : ctx_(NULL)
  49 {
  50   Lock lock(mutex_);
  51
  52   gcry_error_t err = gcry_md_open( &ctx_, GCRY_MD_SHA1, GCRY_MD_FLAG_HMAC );
  53   if( err )
  54     cLog.msg(Log::PRIO_CRIT) << "Sha1AuthAlgo::Sha1AuthAlgo: Failed to open message digest algo";
  55 }
  56
  57 Sha1AuthAlgo::~Sha1AuthAlgo()
  58 {
  59   Lock lock(mutex_);
  60
  61   gcry_md_close( ctx_ );
  62   cLog.msg(Log::PRIO_DEBUG) << "Sha1AuthAlgo::~Sha1AuthAlgo: closed hmac handler";
  63 }
  64
  65 void Sha1AuthAlgo::setKey(Buffer key)
  66 {
  67   Lock lock(mutex_);
  68
  69   gcry_error_t err;
  70   err = gcry_md_setkey( ctx_, key.getBuf(), key.getLength() );
  71   if( err )
  72     cLog.msg(Log::PRIO_ERR) << "Sha1AuthAlgo::setKey: Failed to set cipher key: " << gpg_strerror( err );
  73 }
  74
  75 AuthTag Sha1AuthAlgo::calc(const Buffer& buf)
  76 {
  77   Lock lock(mutex_);
  78
  79   // gcry_error_t err;
  80   AuthTag hmac(10);      // 10byte
  81   gcry_mpi_t tmp = gcry_mpi_new(160);   // 20byte
  82
  83   gcry_md_write( ctx_, static_cast<Buffer>(buf).getBuf(), buf.getLength() );
  84   gcry_md_final( ctx_ );
  85   gcry_mpi_scan( &tmp, GCRYMPI_FMT_STD, gcry_md_read(ctx_, 0), 20, NULL );
  86   gcry_mpi_clear_highbit( tmp, 81 );    // truncate hmac from 20byte to 10byte
  87   gcry_mpi_print( GCRYMPI_FMT_STD, hmac, hmac.getLength(), NULL, tmp );
  88   return hmac;
  89 }
  90
  91