wiselib.testing/algorithms/crypto/ZeroKnowledgeProofsFp/schnorr-zkp-prover.h

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/***************************************************************************
 ** This file is part of the generic algorithm library Wiselib.           **
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 ** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         **
 ** GNU Lesser General Public License for more details.                   **
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#ifndef __ALGORITHMS_CRYPTO_SCHNORRZKP_PROVER_H_
#define __ALGORITHMS_CRYPTO_SHCNORRZKP_PROVER_H_


#include "algorithms/crypto/eccfp.h"
#include <string.h>

//Uncomment to enable Debug
#define ENABLE_SCHNORRZKP_DEBUG

/* PROTOCOL DESCRIPTION

Schnorr's Protocol

Prover and Verifier agree on an elliptic curve E over a field Fn , a generator
G in E/Fn . They both know B in E/Fn and Prover claims he knows x such
that B = x * G.

Protocol Steps

1. Prover generates random r and computes A = r * G
2. Prover sends A to Verifier
3. Verifier computes c = HASH(G, B, A) and sends c to Prover
4. Prover computes m = r + cx and sends m to Verifier
5 Verifier checks that P = m*G-c*B =(r+cx)*G-c*B = r*G+cx*G - c*xG = A
and that HASH(G, B, P ) = c.
*/

namespace wiselib {

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

      typedef SCHNORRZKPProve<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;

      SCHNORRZKPProve();
      ~SCHNORRZKPProve();

      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(NN_DIGIT *privkey , Point *pubkey);
      void start_proof();
      void send_key();

   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;

   //rounds of the protocol used for seeding the rand function
   uint16_t rounds;

   //private key that only the prover knows
   NN_DIGIT m[NUMWORDS];

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

   //private key r that is generated in every round and
   //its corresponding public key
   NN_DIGIT r[NUMWORDS];
   Point Verify;

   //the hash that will be received from verifier
   NN_DIGIT Hash[NUMWORDS];

   //data that will be sent to the verifier
   NN_DIGIT x[NUMWORDS];

   };

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

   // -----------------------------------------------------------------------
   template<typename OsModel_P,
      typename Radio_P,
      typename Debug_P>
   SCHNORRZKPProve<OsModel_P, Radio_P, Debug_P>::
	~SCHNORRZKPProve()
   {}
   //-----------------------------------------------------------------------
   template<typename OsModel_P,
         typename Radio_P,
         typename Debug_P>
   int
   SCHNORRZKPProve<OsModel_P, Radio_P, Debug_P>::
   init( void )
   {
     enable_radio();
     return 0;
   }
   //-----------------------------------------------------------------------------
   template<typename OsModel_P,
         typename Radio_P,
         typename Debug_P>
   int
   SCHNORRZKPProve<OsModel_P, Radio_P, Debug_P>::
   destruct( void )
   {
     return disable_radio();
   }
   //---------------------------------------------------------------------------
   template<typename OsModel_P,
         typename Radio_P,
         typename Debug_P>
   int
   SCHNORRZKPProve<OsModel_P, Radio_P, Debug_P>::
   enable_radio( void )
   {
#ifdef ENABLE_SCHNORRZKP_DEBUG
     debug().debug( "Debug::SCHNORR-ZKPProve: 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
   SCHNORRZKPProve<OsModel_P, Radio_P, Debug_P>::
   disable_radio( void )
   {
#ifdef ENABLE_SCHNORRZKP_DEBUG
     debug().debug( "SCHNORR-ZKPProve: Disable\n" );
#endif
     return -1;
   }
   //-----------------------------------------------------------------------
   template<typename OsModel_P,
            typename Radio_P,
            typename Debug_P>
   void
   SCHNORRZKPProve<OsModel_P, Radio_P, Debug_P>::
	key_setup( NN_DIGIT *privkey , Point *pubkey  ) {

      rounds=1;

      //copy the keys to the local variables
      pmp.AssignZero(m, NUMWORDS);
      pmp.Assign(m, privkey, NUMWORDS);

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

   //---------------------------------------------------------------------------
   template<typename OsModel_P,
            typename Radio_P,
            typename Debug_P>
   void
   SCHNORRZKPProve<OsModel_P, Radio_P, Debug_P>::
	start_proof( void ) {

#ifdef ENABLE_SCHNORRZKP_DEBUG
      debug().debug("Debug::Starting Schnorr Interactive ZKP Prover on::%d \n", radio().id() );
#endif

      //if the protocol is booting generate random r and compute A=rG
      //and send A  to verifier
      rounds++;

      //clear private and public key
      pmp.AssignZero(r, NUMWORDS);
      eccfp.p_clear(&Verify);

#ifdef ENABLE_SCHNORRZKP_DEBUG
      debug().debug("Debug::Generating random r and compute A=rG. ::%d \n", radio().id() );
#endif

      //generate random r and compute pubKey A=rG
      eccfp.gen_private_key(r, rounds);
      eccfp.gen_public_key(&Verify, r);

      //place the verify key in the buffer and send the message
      block_data_t msg[2*(KEYDIGITS*NN_DIGIT_LEN + 1) + 1];
      msg[0]=START_MSG;

      //convert point to octet
      eccfp.point2octet(msg+1, 2*(KEYDIGITS*NN_DIGIT_LEN + 1), &Verify, FALSE);

#ifdef ENABLE_SCHNORRZKP_DEBUG
      debug().debug("Debug::Finished calculations!Sending verify key to verifier. ::%d \n", radio().id() );
#endif
      radio().send(Radio::BROADCAST_ADDRESS, 2*(KEYDIGITS*NN_DIGIT_LEN + 1) +1, msg);
   }

   //------------------------------------------------------------------------
   template<typename OsModel_P,
            typename Radio_P,
            typename Debug_P>
   void
   SCHNORRZKPProve<OsModel_P, Radio_P, Debug_P>::
	send_key( void ) {

#ifdef ENABLE_SCHNORRZKP_DEBUG
      debug().debug("Debug::Creating the new private key ::%d \n", radio().id() );
#endif

      //prover computes x= r + cm
      //and sends x to verifier

      //clear private key x
      pmp.AssignZero(x, NUMWORDS);

      NN_DIGIT mid2[NUMWORDS];
      pmp.AssignZero(mid2, NUMWORDS);

      //first compute cm
      pmp.ModMult(mid2, Hash, m, param.r, NUMWORDS);
      //then add r+cm
      pmp.ModAdd(x, r, mid2, param.r, NUMWORDS);

      //send the message with x to verifier
      //if it is tails send to verifier m+r
      block_data_t buffer[KEYDIGITS*NN_DIGIT_LEN + 2];
      buffer[0]=CONT_MSG;

      //convert x to octet
      pmp.Encode(buffer+1, KEYDIGITS * NN_DIGIT_LEN +1, x, NUMWORDS);

#ifdef ENABLE_SCHNORRZKP_DEBUG
      debug().debug("Debug::Sending the new private key x to verifier::%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>
   void
   SCHNORRZKPProve<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]==HASH_MSG)
      {

#ifdef ENABLE_SCHNORRZKP_DEBUG
         debug().debug("Debug::Received a hash message. Calling the send_key task.::%d \n", radio().id() );
#endif

         //clear the private key and store it
         pmp.AssignZero(Hash, NUMWORDS);
         //decode the private key received
         pmp.Decode(Hash, NUMWORDS, data+1, KEYDIGITS * NN_DIGIT_LEN +1);

         //calling the send_key task
         send_key();
      }

      if(data[0]==ACCEPT_MSG)
      {
#ifdef ENABLE_SCHNORRZKP_DEBUG
         debug().debug("Debug::I got ACCEPTED from the verifier.YESSS!::%d \n", radio().id() );
#endif
      }

      if(data[0]==REJECT_MSG)
      {
#ifdef ENABLE_SCHNORRZKP_DEBUG
         debug().debug("Debug::I got REJECTED from the verifier.NOOO!::%d \n", radio().id() );
#endif
      }

   }

} //end of wiselib namespace

#endif /* SCHNORRZKP_PROVER_H_ */