wiselib.testing/algorithms/crypto/ZeroKnowledgeProofsFp/TestofDLEquality-verifier.h

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/***************************************************************************
 ** This file is part of the generic algorithm library Wiselib.           **
 ** Copyright (C) 2008,2009 by the Wisebed (www.wisebed.eu) project.      **
 **                                                                       **
 ** The Wiselib is free software: you can redistribute it and/or modify   **
 ** it under the terms of the GNU Lesser General Public License as        **
 ** published by the Free Software Foundation, either version 3 of the    **
 ** License, or (at your option) any later version.                       **
 **                                                                       **
 ** The Wiselib is distributed in the hope that it will be useful,        **
 ** but WITHOUT ANY WARRANTY; without even the implied warranty of        **
 ** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         **
 ** GNU Lesser General Public License for more details.                   **
 **                                                                       **
 ** You should have received a copy of the GNU Lesser General Public      **
 ** License along with the Wiselib.                                       **
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 ***************************************************************************/

#ifndef __ALGORITHMS_TESTOFDLEQUALITY_VERIFIER_H_
#define __ALGORITHMS_TESTOFDLEQUALITY_VERIFIER_H_

#include "algorithms/crypto/eccfp.h"

#include <string.h>

//protocol needs to be executed for 1 round
#define REQ_ROUNDS 1

// Uncomment to enable Debug
#define ENABLE_TESTOFDLEQUALITY_DEBUG

/*PROTOCOL DESCRIPTION

Zero Knowledge Test of Discrete Logarithm Equality

Prover and Verifier agree on an elliptic curve E over a field Fn , a generator
G in E/Fn and H in E/Fn . Prover claims he knows x such that B = x*G and
C = x*H and wants to prove knowledge without revaling x.

Protocol Steps

1. Prover chooses random r and computes K = r*G and L = r*H
2. Prover sends points K, L to Verifier
3. Verifier chooses random c and sends c to Prover
4. Prover computes m = r + cx and sends m to Verfier
5. Verifier checks that m*G = (r + cx)*G = r*G + c*xG = K + cB
6. Verifier checks that m*H = (r + cx)*H = r*H + c*xH = L + cC
*/

namespace wiselib{

template<typename OsModel_P, typename Radio_P = typename OsModel_P::Radio, typename Debug_P = typename OsModel_P::Debug>
   class TESTOFDLEQUALITYVerify
   {
   public:
      typedef OsModel_P OsModel;
      typedef Radio_P Radio;
      typedef Debug_P Debug;

      typedef TESTOFDLEQUALITYVerify<OsModel_P, Radio_P, Debug_P> self_t;
     typedef typename Radio::node_id_t node_id_t;
     typedef typename Radio::size_t size_t;
     typedef typename Radio::block_data_t block_data_t;
     typedef self_t* self_pointer_t;

      TESTOFDLEQUALITYVerify();
      ~TESTOFDLEQUALITYVerify();


      int init( Radio& radio, Debug& debug )
     {
       radio_ = &radio;
       debug_ = &debug;
       return 0;
     }

     inline int init();
     inline int destruct();

     int enable_radio( void );
     int disable_radio( void );

      //message types
      enum MsgHeaders {
        START_MSG = 200,
        HASH_MSG = 201,
        CONT_MSG = 202,
        ACCEPT_MSG = 203,
        REJECT_MSG = 204
       };

      void key_setup(Point *pubkey, Point *pubkey1, Point *pubkey2);
      void generate_random();
      bool verify();
      bool verify_msg();
      void final_decision();

   protected:
           void receive( node_id_t from, size_t len, block_data_t *data );

   private:

   Radio& radio()
   { return *radio_; }

   Debug& debug()
   { return *debug_; }

   typename Radio::self_pointer_t radio_;
   typename Debug::self_pointer_t debug_;

   //necessary class objects
   ECCFP eccfp;
   PMP pmp;

    //# of rounds (used for seeding and generating the random value)
   uint8_t rounds;

      //# of successfull rounds
   uint8_t success_rounds;

   //# of required rounds
   uint8_t required_rounds;

   //the random private key calculated on the point received by the prover
   NN_DIGIT c[NUMWORDS];

   //private key that will be received by the prover in each round
   NN_DIGIT Valid[NUMWORDS];

   //public key that both prover and verifier know
   Point B;
   Point P;
   Point C;

   //public key A to be received by the prover
   Point K;
   Point L;

   //public key Check for the verifications
   Point Check;
   Point Check2;

   };

   // -----------------------------------------------------------------------
   template<typename OsModel_P,
         typename Radio_P,
         typename Debug_P>
   TESTOFDLEQUALITYVerify<OsModel_P, Radio_P, Debug_P>::
	TESTOFDLEQUALITYVerify()
   : radio_(0),
     debug_(0)
   {}

   // -----------------------------------------------------------------------
   template<typename OsModel_P,
         typename Radio_P,
         typename Debug_P>
   TESTOFDLEQUALITYVerify<OsModel_P, Radio_P, Debug_P>::
	~TESTOFDLEQUALITYVerify()
   {}

   //-----------------------------------------------------------------------
   template<typename OsModel_P,
               typename Radio_P,
               typename Debug_P>
   int
   TESTOFDLEQUALITYVerify<OsModel_P, Radio_P, Debug_P>::
	init( void )
   {
     enable_radio();
     return 0;
   }
   //-----------------------------------------------------------------------------
   template<typename OsModel_P,
         typename Radio_P,
         typename Debug_P>
   int
   TESTOFDLEQUALITYVerify<OsModel_P, Radio_P, Debug_P>::
	destruct( void )
   {
     return disable_radio();
   }
   //---------------------------------------------------------------------------
   template<typename OsModel_P,
         typename Radio_P,
         typename Debug_P>
   int
   TESTOFDLEQUALITYVerify<OsModel_P, Radio_P, Debug_P>::
	enable_radio( void )
   {
#ifdef ENABLE_TESTOFDLEQUALITY_DEBUG
      debug().debug( "ZKP Test of Dl Verify: Boot for %i\n", radio().id() );
#endif

     radio().enable_radio();
     radio().template reg_recv_callback<self_t, &self_t::receive>( this );

     return 0;
   }
   //---------------------------------------------------------------------------
   template<typename OsModel_P,
         typename Radio_P,
         typename Debug_P>
   int
   TESTOFDLEQUALITYVerify<OsModel_P, Radio_P, Debug_P>::
	disable_radio( void )
   {
#ifdef ENABLE_TESTOFDLEQUALITY_DEBUG
      debug().debug( "ZKP Test of Dl Prove: Disable\n" );
#endif
     return -1;
   }
   //----------------------------------------------------------------------
   template<typename OsModel_P,
            typename Radio_P,
            typename Debug_P>
   void
   TESTOFDLEQUALITYVerify<OsModel_P, Radio_P, Debug_P>::
	key_setup( Point *pubkey, Point *pubkey1, Point *pubkey2 ) {

#ifdef ENABLE_TESTOFDLEQUALITY_DEBUG
      debug().debug("Debug::Start Test of DL equality Interactive ZKP Verifier on::%d \n", radio().id() );
#endif
      rounds=89;
      success_rounds=0;
      required_rounds=REQ_ROUNDS;

      //get first public key available to prover and verifier
      eccfp.p_clear(&B);
      eccfp.p_copy(&B, pubkey);

      //second generator P
      eccfp.p_clear(&P);
      eccfp.p_copy(&P, pubkey1);

      //get second public key C with m as EC discrete log (C=mP)
      eccfp.p_clear(&C);
      eccfp.p_copy(&C, pubkey2);
   }

   //------------------------------------------------------------------------------------
   template<typename OsModel_P,
               typename Radio_P,
               typename Debug_P>
   void
   TESTOFDLEQUALITYVerify<OsModel_P, Radio_P, Debug_P>::
	generate_random(){
#ifdef ENABLE_TESTOFDLEQUALITY_DEBUG
      debug().debug("Debug::Generating random number c!\n", radio().id() );
#endif

      //clear the private key c
      pmp.AssignZero(c, NUMWORDS);
      //and generate random number c
      eccfp.gen_private_key(c, rounds);

      //send message with c to prover
      uint8_t buffer[KEYDIGITS*NN_DIGIT_LEN+2];
      buffer[0]=HASH_MSG;
      //place key to buffer after encoding to octet
      pmp.Encode(buffer+1, KEYDIGITS * NN_DIGIT_LEN +1, c, NUMWORDS);

#ifdef ENABLE_TESTOFDLEQUALITY_DEBUG
      debug().debug( "Debug::Finished generating random number c!Sending c to prover. ::%d \n", radio().id() );
#endif

      radio().send( Radio::BROADCAST_ADDRESS, KEYDIGITS*NN_DIGIT_LEN+2, buffer);
   }

   //------------------------------------------------------------------------------------
   template<typename OsModel_P,
            typename Radio_P,
            typename Debug_P>
   bool
   TESTOFDLEQUALITYVerify<OsModel_P, Radio_P, Debug_P>::
	verify(){
#ifdef ENABLE_TESTOFDLEQUALITY_DEBUG
      debug().debug("Debug::Starting first Verification!\n", radio().id() );
#endif

      //verifier checks that sG = K + cB
      Point result;
      Point result1;
      eccfp.p_clear(&result);
      eccfp.p_clear(&result1);
      eccfp.p_clear(&Check);

      //compute sG
      eccfp.gen_public_key(&result, Valid);

      //compute cB
      eccfp.c_mul(&result1, &B, c);

      //compute K + cB
      eccfp.c_add_affine(&Check, &K, &result1);

      //is the result correct???
      //compare point sG with point K+cB
      if(eccfp.p_equal(&result, &Check)==true)
      {
#ifdef ENABLE_TESTOFDLEQUALITY_DEBUG
         debug().debug("Debug::First check SUCCESS!\n", radio().id() );
#endif
         verify_msg();
         return true;
      }
      else
      {
#ifdef ENABLE_TESTOFDLEQUALITY_DEBUG
         debug().debug( "Debug::First check FAIL!\n", radio().id() );
#endif
         final_decision();
         return false;
      }
   }

   //-------------------------------------------------------------------------------------
   template<typename OsModel_P,
            typename Radio_P,
            typename Debug_P>
   bool
   TESTOFDLEQUALITYVerify<OsModel_P, Radio_P, Debug_P>::
	verify_msg(){

#ifdef ENABLE_TESTOFDLEQUALITY_DEBUG
      debug().debug("Debug::Starting second verification!\n", radio().id() );
#endif
      //verifier checks that sP = L + cC
      Point result;
      Point result1;
      eccfp.p_clear(&result);
      eccfp.p_clear(&result1);
      eccfp.p_clear(&Check2);

      //compute sP
      eccfp.c_mul(&result, &P, Valid);

      //compute cC
      eccfp.c_mul(&result1, &C, c);

      //compute L + cC
      eccfp.c_add_affine(&Check2, &L, &result1);

      //is the result correct???
      //compare sP with L + cC
      if(eccfp.p_equal(&Check2, &result)==true)
      {
#ifdef ENABLE_TESTOFDLEQUALITY_DEBUG
         debug().debug( "Debug::Second check SUCCESS!\n", radio().id());
#endif
         success_rounds++;
         final_decision();
         return true;
      }
      else
      {
#ifdef ENABLE_TESTOFDLEQUALITY_DEBUG
         debug().debug( "Debug::Second check FAIL!\n", radio().id() );
#endif
         final_decision();
         return false;
      }
   }

   //----------------------------------------------------------------------------------------
   template<typename OsModel_P,
            typename Radio_P,
            typename Debug_P>
   void
   TESTOFDLEQUALITYVerify<OsModel_P, Radio_P, Debug_P>::
	final_decision(){

      //were the round successful??the protocol accepts
      if(success_rounds==required_rounds)
      {
#ifdef ENABLE_TESTOFDLEQUALITY_DEBUG
         debug().debug("Debug::Protocol finished with success.Secret Verified!!Prover HONEST!\n", radio().id() );
#endif
         //send to prover the accept message
         block_data_t buffer[1];
         buffer[0]=ACCEPT_MSG;
         radio().send(Radio::BROADCAST_ADDRESS,1,buffer);
      }
      //the round failed, the protocol rejects
      else
      {
#ifdef ENABLE_TESTOFDLEQUALITY_DEBUG
         debug().debug("Debug::Protocol finished without success.Secret NOT Verified!!Prover NOT HONEST\n", radio().id() );
#endif
         block_data_t buffer[1];
         buffer[0]=REJECT_MSG;
         radio().send(Radio::BROADCAST_ADDRESS,1,buffer);
      }
   }

   //---------------------------------------------------------------------------
   template<typename OsModel_P,
            typename Radio_P,
            typename Debug_P>
   void
   TESTOFDLEQUALITYVerify<OsModel_P, Radio_P, Debug_P>::
	receive( node_id_t from, size_t len, block_data_t *data ) {

      if( from == radio().id() ) return;

      if(data[0]==START_MSG)
      {
#ifdef ENABLE_TESTOFDLEQUALITY_DEBUG
         debug().debug("Debug::Received a starting message::%d \n", radio().id());
#endif

         //get points K and L
         eccfp.p_clear(&K);
         eccfp.p_clear(&L);
         //copy the two keys received after decoding
         eccfp.octet2point(&K, data+1, 2*(KEYDIGITS * NN_DIGIT_LEN +1));
         eccfp.octet2point(&L, data+2*(KEYDIGITS * NN_DIGIT_LEN +1)+1, 2*(KEYDIGITS * NN_DIGIT_LEN +1));

         //call the task to compute random c
         generate_random();
      }

      if(data[0]==CONT_MSG)
      {
#ifdef ENABLE_TESTOFDLEQUALITY_DEBUG
         debug().debug("Debug::Received a continue message::%d \n", radio().id() );
#endif

         //get private key x
         pmp.AssignZero(Valid, NUMWORDS);
         //decode the private key received
         pmp.Decode(Valid, NUMWORDS, data+1, KEYDIGITS * NN_DIGIT_LEN +1);

         //call verify
         verify();

      }

   }

} //end of wiselib namespace

#endif /* TESTOFDLEQUALITY_VERIFIER_H_ */