wiselib.testing/algorithms/crypto/ZeroKnowledgeProofsFp/schnorr-zkpnint-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.      **
 **                                                                       **
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 ** 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_CRYPTO_ZKPVERIFIER_H_
#define __ALGORITHMS_CRYPTO_ZKPVERIFIER_H_

#include "algorithms/crypto/eccfp.h"
#include "algorithms/crypto/pmp.h"
#include "algorithms/crypto/sha1.h"

#include <string.h>

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

// Uncomment to enable Debug
#define ENABLE_ZKPNINT_DEBUG

/* PROTOCOL DESCRIPTION

Non-interactive Schnorr's Protocol

Prover and Verifier agree on an elliptic curve E over a field Fn , a generator
G in E/Fn , P in E/Fn and a hash function HASH (e.g. SHA-1). Both know
B in E/Fn and Prover claims that he knows x such that B = x*G.

Protocol Steps

1. Prover generates random r and computes A = r*G
2. Prover computes c = HASH(x*P, r*P, r*G)
3. Prover computes s = r + cx
4. Prover sends to Verifier the message : " s||x*P ||r*P ||r*G "
5. Verifier computes c = HASH(x*P, r*P, r*G)
6. Verifier checks that s*G = (r + cx)*G = r*G + cx*G = r*G + c*B
7. Verifier checks that s*P = (r + cx)*P = r*P + cx*P = r*P + c*xP
*/

namespace wiselib {

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

      typedef ZKPNINTVerify<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;

      ZKPNINTVerify();
      ~ZKPNINTVerify();


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

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

      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 );

   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 successfull rounds
   uint8_t success_rounds;

   //# of required rounds
   uint8_t required_rounds;

   //the hash calculated on the points received by the prover
   NN_DIGIT c[NUMWORDS];

   //private key that will be received by the prover
   NN_DIGIT s[NUMWORDS];

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

   //public key that represents the message
   Point P;

   //public keys mP and rP and A to be received by the prover
   Point A;
   Point MP;
   Point RP;

   };

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

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

   //-----------------------------------------------------------------------
   template<typename OsModel_P,
         typename Radio_P,
         typename Debug_P>
   int
   ZKPNINTVerify<OsModel_P, Radio_P, Debug_P>::
	init( void )
   {
     enable_radio();
     return 0;
   }
   //-----------------------------------------------------------------------------
   template<typename OsModel_P,
         typename Radio_P,
         typename Debug_P>
   int
   ZKPNINTVerify<OsModel_P, Radio_P, Debug_P>::
	destruct( void )
   {
     return disable_radio();
   }
   //---------------------------------------------------------------------------
   template<typename OsModel_P,
         typename Radio_P,
         typename Debug_P>
   int
   ZKPNINTVerify<OsModel_P, Radio_P, Debug_P>::
	enable_radio( void )
   {
#ifdef ENABLE_ZKPNINT_DEBUG
      debug().debug( "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
   ZKPNINTVerify<OsModel_P, Radio_P, Debug_P>::
	disable_radio( void )
   {
#ifdef ENABLE_ZKPNINT_DEBUG
      debug().debug( "ZKPProve: Disable\n" );
#endif
     return -1;
   }

   //----------------------------------------------------------------------
   template<typename OsModel_P,
            typename Radio_P,
            typename Debug_P>
   void
   ZKPNINTVerify<OsModel_P, Radio_P, Debug_P>::
	key_setup( Point *pubkey, Point *pubkey2 ) {

#ifdef ENABLE_ZKPNINT_DEBUG
      debug().debug("Debug::Start ZKP Non-interactive Verifier on::%d \n", radio().id() );
#endif
      success_rounds=0;
      required_rounds=REQ_ROUNDS;

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

      //message available to prover and verifier
      eccfp.p_clear(&P);
      eccfp.p_copy(&P, pubkey2);

   }

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

      //compute c=HASH(mP, rP, A)
      block_data_t input[6*(KEYDIGITS * NN_DIGIT_LEN +1)];
      for(int16_t i=0; i< 6*(KEYDIGITS*NN_DIGIT_LEN +1); i++)
      {
         input[i]=0;
      }
      block_data_t b[20];
      //convert point mP to octet and place to input
      eccfp.point2octet(input, 2*(KEYDIGITS*NN_DIGIT_LEN + 1), &MP, FALSE);
      //convert point rP to octet and place to input
      eccfp.point2octet(input + 2*(KEYDIGITS*NN_DIGIT_LEN + 1), 2*(KEYDIGITS*NN_DIGIT_LEN + 1), &RP, FALSE);
      //convert point A to octet and place to input
      eccfp.point2octet(input + 4*(KEYDIGITS*NN_DIGIT_LEN + 1), 2*(KEYDIGITS*NN_DIGIT_LEN + 1), &A, FALSE);

      //digest
      SHA1Context sha;
      SHA1::SHA1Reset(&sha);
      SHA1::SHA1Update(&sha, input, 6*(KEYDIGITS * NN_DIGIT_LEN +1));
      SHA1::SHA1Digest(&sha, b);

      //place the hash in a key
      NN_DIGIT key[NUMWORDS];
      pmp.AssignZero(key, NUMWORDS);
      //decode the private key received
      pmp.Decode(key, NUMWORDS, b, 20);
      //mod n the hash output
      pmp.AssignZero(c, NUMWORDS);
      pmp.Mod(c, key, NUMWORDS, param.r, NUMWORDS);

      //check that sG = A + cB
      Point result;
      Point result1;
      Point result2;
      eccfp.p_clear(&result);
      eccfp.p_clear(&result1);
      eccfp.p_clear(&result2);

      //compute sG
      eccfp.gen_public_key(&result, s);
      //compute cB
      eccfp.c_mul(&result1, &B, c);
      //compute A + cB
      eccfp.c_add_affine(&result2, &A, &result1);

      //is the result correct???
      if(eccfp.p_equal(&result, &result2)==true)
      {
#ifdef ENABLE_ZKPNINT_DEBUG
         debug().debug("Debug::First check SUCCESS!\n", radio().id() );
#endif
         verify_msg();
         return true;
      }
      else
      {
#ifdef ENABLE_ZKPNINT_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
   ZKPNINTVerify<OsModel_P, Radio_P, Debug_P>::
	verify_msg(){

#ifdef ENABLE_ZKPNINT_DEBUG
      debug().debug("Debug::Starting verify message!\n", radio().id() );
#endif

      //now check that sP = rP + cmP
      Point result;
      Point result1;
      Point result2;
      eccfp.p_clear(&result);
      eccfp.p_clear(&result1);
      eccfp.p_clear(&result2);

      //compute sP
      eccfp.c_mul(&result, &P, s);
      //compute c*MP
      eccfp.c_mul(&result1, &MP, c);
      //compute rP + cMP
      eccfp.c_add_affine(&result2, &RP, &result1);

      //is the result correct???
      if(eccfp.p_equal(&result, &result2)==true)
      {
#ifdef ENABLE_ZKPNINT_DEBUG
         debug().debug("Debug::Second check SUCCESS!\n", radio().id() );
#endif
         success_rounds++;
         final_decision();
         return true;
      }
      else
      {
#ifdef ENABLE_ZKPNINT_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
   ZKPNINTVerify<OsModel_P, Radio_P, Debug_P>::
	final_decision(){

      //were the round successful??the protocol accepts
      if(success_rounds==required_rounds)
      {
#ifdef ENABLE_ZKPNINT_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);
      }
      //some rounds failed, the protocol rejects
      else
      {
#ifdef ENABLE_ZKPNINT_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
   ZKPNINTVerify<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_ZKPNINT_DEBUG
         debug().debug("Debug::Received a starting message::%d \n", radio().id() );
#endif
         //get s and point mP

         //first get s and clear Valid
         //then get s and place to Valid
         pmp.AssignZero(s, NUMWORDS);
         //decode the private key received
         pmp.Decode(s, NUMWORDS, data+1, KEYDIGITS * NN_DIGIT_LEN +1);

         //then get point mP
         eccfp.p_clear(&MP);
         //convert octet received to point MP
         eccfp.octet2point(&MP, data+ 1 + (KEYDIGITS*NN_DIGIT_LEN+1), 2*(KEYDIGITS * NN_DIGIT_LEN +1));
      }

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

         //first get rP
         eccfp.p_clear(&RP);
         eccfp.octet2point(&RP, data+1, 2*(KEYDIGITS * NN_DIGIT_LEN +1));

         //then get rG
         eccfp.p_clear(&A);
         eccfp.octet2point(&A, data+ 1 + 2*(KEYDIGITS*NN_DIGIT_LEN+1), 2*(KEYDIGITS * NN_DIGIT_LEN +1));

#ifdef ENABLE_ZKPNINT_DEBUG
         debug().debug("Debug::Calling the function verify()::%d \n", radio().id() );
#endif
         //call verify
         verify();
      }

   }

} //end of namespace

#endif /* ZKP_VERIFIER_H_ */