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128 lines
2.6 KiB
C++
128 lines
2.6 KiB
C++
/*
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* Shamir.cpp
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*
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*/
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#include "Shamir.h"
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#include "ShamirInput.h"
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#include "Machines/ShamirMachine.h"
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template<class U>
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U Shamir<U>::get_rec_factor(int i, int n)
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{
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U res = 1;
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for (int j = 0; j < n; j++)
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if (i != j)
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res *= U(j + 1) / (U(j + 1) - U(i + 1));
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return res;
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}
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template<class U>
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Shamir<U>::Shamir(Player& P) : resharing(0), P(P)
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{
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threshold = ShamirMachine::s().threshold;
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n_mul_players = 2 * threshold + 1;
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}
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template<class U>
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Shamir<U>::~Shamir()
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{
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if (resharing != 0)
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delete resharing;
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}
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template<class U>
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int Shamir<U>::get_n_relevant_players()
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{
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return ShamirMachine::s().threshold + 1;
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}
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template<class U>
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void Shamir<U>::reset()
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{
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os.clear();
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os.resize(P.num_players());
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if (resharing == 0)
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{
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resharing = new ShamirInput<T>(0, P);
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}
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for (int i = 0; i < P.num_players(); i++)
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resharing->reset(i);
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}
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template<class U>
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void Shamir<U>::init_mul(SubProcessor<T>* proc)
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{
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(void) proc;
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reset();
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if (rec_factor == 0 and P.my_num() < n_mul_players)
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rec_factor = get_rec_factor(P.my_num(), n_mul_players);
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}
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template<class U>
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U Shamir<U>::prepare_mul(const T& x, const T& y)
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{
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auto add_share = x * y * rec_factor;
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if (P.my_num() < n_mul_players)
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resharing->add_mine(add_share);
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return add_share;
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}
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template<class U>
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void Shamir<U>::exchange()
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{
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if (P.my_num() < n_mul_players)
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resharing->send_mine();
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for (int i = 0; i < n_mul_players; i++)
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if (i != P.my_num())
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P.receive_player(i, os[i], true);
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}
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template<class U>
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ShamirShare<U> Shamir<U>::finalize_mul()
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{
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return finalize(n_mul_players);
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}
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template<class U>
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ShamirShare<U> Shamir<U>::finalize(int n_relevant_players)
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{
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ShamirShare<U> res = U(0);
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if (P.my_num() < n_relevant_players)
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res = resharing->finalize_mine();
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for (int i = 0; i < n_relevant_players; i++)
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if (i != P.my_num())
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{
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T tmp;
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resharing->finalize_other(i, tmp, os[i]);
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res += tmp;
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}
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return res;
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}
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template<class U>
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ShamirShare<U> Shamir<U>::get_random()
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{
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if (random.empty())
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buffer_random();
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auto res = random.back();
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random.pop_back();
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return res;
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}
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template<class U>
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void Shamir<U>::buffer_random()
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{
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Shamir<U> shamir(P);
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shamir.reset();
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int buffer_size = 1000;
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if (P.my_num() <= threshold)
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for (int i = 0; i < buffer_size; i++)
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shamir.resharing->add_mine(secure_prng.get<U>());
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shamir.exchange();
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for (int i = 0; i < buffer_size; i++)
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random.push_back(shamir.finalize(threshold + 1));
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}
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