PRSONA/prsona/inc/client.hpp

#ifndef __PRSONA_CLIENT_HPP
#define __PRSONA_CLIENT_HPP

#include <unordered_map>
#include <vector>

#include "Curvepoint.hpp"
#include "Scalar.hpp"
#include "BGN.hpp"

#include "EGCiphertext.hpp"
#include "proof.hpp"

// Forward declaration to be able to make a pointer to the servers,
// which is needed in some proofs
class PrsonaServerEntity;

class PrsonaClient {
    public:
        // CONSTRUCTORS
        PrsonaClient(
            const BGNPublicKey& serverPublicKey,
            const Curvepoint& elGamalBlindGenerator,
            const PrsonaServerEntity *servers);

        // SETUP FUNCTIONS
        static void init();
        static void set_server_malicious();
        static void set_client_malicious();

        // BASIC PUBLIC SYSTEM INFO GETTERS
        Curvepoint get_short_term_public_key(Proof &pi) const;

        // SERVER INTERACTIONS
        std::vector<CurveBipoint> make_votes(
            std::vector<Proof>& validVoteProof,
            const Proof& serverProof,
            const std::vector<CurveBipoint>& oldEncryptedVotes,
            const std::vector<Scalar>& votes,
            const std::vector<bool>& replaces
        ) const;
        void receive_fresh_generator(const Curvepoint& freshGenerator);
        void receive_vote_tally(const Proof& pi, const EGCiphertext& score);
        
        // REPUTATION PROOFS
        std::vector<Proof> generate_reputation_proof(
            const Scalar& threshold) const;
        bool verify_reputation_proof(
            const std::vector<Proof>& pi,
            const Curvepoint& shortTermPublicKey,
            const Scalar& threshold) const;

        Scalar get_score() const;

    private:
        // Constants for clients
        static Curvepoint EL_GAMAL_GENERATOR;
        static bool SERVER_IS_MALICIOUS;
        static bool CLIENT_IS_MALICIOUS;
        
        // Things bound to the servers permanently
        const BGNPublicKey serverPublicKey;
        const Curvepoint elGamalBlindGenerator;
        const PrsonaServerEntity *servers;

        // Things bound to the servers (but change regularly)
        Curvepoint currentFreshGenerator;

        // Things bound to this user permanently
        Scalar longTermPrivateKey;
        Scalar inversePrivateKey;

        // Things bound to this user (but change regularly)
        EGCiphertext currentEncryptedScore;
        Scalar currentScore;

        // Things related to making decryption more efficient
        std::unordered_map<Curvepoint, Scalar, CurvepointHash>
            decryption_memoizer;
        Scalar max_checked;

        // SCORE DECRYPTION
        void decrypt_score(const EGCiphertext& score);

        // OWNERSHIP OF STPK PROOFS
        Proof generate_ownership_proof() const;
        bool verify_ownership_proof(
            const Proof& pi, const Curvepoint& shortTermPublicKey) const;

        // PROOF VERIFICATION
        bool verify_score_proof(const Proof& pi) const;
        bool verify_generator_proof(
            const Proof& pi, const Curvepoint& generator) const;
        bool verify_default_tally_proof(
            const Proof& pi, const EGCiphertext& generator) const;
        bool verify_valid_tally_proof(
            const Proof& pi, const EGCiphertext& score) const;
        bool verify_default_votes_proof(
            const Proof& pi, const std::vector<CurveBipoint>& votes) const;
        bool verify_valid_votes_proof(
            const Proof& pi, const std::vector<CurveBipoint>& votes) const;

        // PROOF GENERATION
        std::vector<Proof> generate_vote_proof(
            const std::vector<bool>& replaces,
            const std::vector<CurveBipoint>& oldEncryptedVotes,
            const std::vector<CurveBipoint>& newEncryptedVotes,
            const std::vector<Scalar>& seeds,
            const std::vector<Scalar>& votes
        ) const;
}; 

#endif