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https://github.com/data61/MP-SPDZ.git
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145 lines
3.3 KiB
C++
145 lines
3.3 KiB
C++
#include "Ciphertext.h"
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#include "P2Data.h"
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#include "Tools/Exceptions.h"
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#include "Tools/CodeLocations.h"
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#include "Math/modp.hpp"
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Ciphertext::Ciphertext(const FHE_PK& pk) : Ciphertext(pk.get_params())
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{
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}
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void Ciphertext::set(const Rq_Element& a0, const Rq_Element& a1,
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const FHE_PK& pk)
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{
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set(a0, a1, pk.a().get(0).get_element(0).get_limb(0));
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}
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word check_pk_id(word a, word b)
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{
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if (a == 0)
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return b;
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else if (b == 0 or a == b)
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return a;
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else
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{
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cout << a << " vs " << b << endl;
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throw runtime_error("public keys of ciphertext operands don't match");
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}
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}
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void Ciphertext::Scale()
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{
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Scale(params->get_plaintext_modulus());
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}
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void add(Ciphertext& ans,const Ciphertext& c0,const Ciphertext& c1)
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{
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if (c0.params!=c1.params) { throw params_mismatch(); }
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if (ans.params!=c1.params) { throw params_mismatch(); }
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ans.pk_id = check_pk_id(c0.pk_id, c1.pk_id);
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add(ans.cc0,c0.cc0,c1.cc0);
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add(ans.cc1,c0.cc1,c1.cc1);
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}
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void sub(Ciphertext& ans,const Ciphertext& c0,const Ciphertext& c1)
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{
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if (c0.params!=c1.params) { throw params_mismatch(); }
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if (ans.params!=c1.params) { throw params_mismatch(); }
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ans.pk_id = check_pk_id(c0.pk_id, c1.pk_id);
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sub(ans.cc0,c0.cc0,c1.cc0);
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sub(ans.cc1,c0.cc1,c1.cc1);
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}
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void mul(Ciphertext& ans,const Ciphertext& c0,const Ciphertext& c1,
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const FHE_PK& pk)
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{
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CODE_LOCATION_NO_SCOPE
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if (c0.params!=c1.params) { throw params_mismatch(); }
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if (ans.params!=c1.params) { throw params_mismatch(); }
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// Switch Modulus for c0 and c1 down to level 0
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Ciphertext cc0=c0,cc1=c1;
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cc0.Scale(pk.p()); cc1.Scale(pk.p());
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// Now do the multiply
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auto d0 = cc0.cc0 * cc1.cc0;
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auto d1 = cc0.cc0 * cc1.cc1 + cc0.cc1 * cc1.cc0;
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auto d2 = cc0.cc1 * cc1.cc1;
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d2.negate();
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// Now do the switch key
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d2.raise_level();
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d0.mul_by_p1();
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auto t = pk.bs()* d2;
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add(d0,d0,t);
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d1.mul_by_p1();
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mul(t,pk.as(),d2);
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add(d1,d1,t);
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ans.set(d0, d1, check_pk_id(c0.pk_id, c1.pk_id));
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ans.Scale(pk.p());
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}
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template<class T,class FD,class S>
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void mul(Ciphertext& ans,const Plaintext<T,FD,S>& a,const Ciphertext& c)
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{
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a.to_poly();
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int lev=c.cc0.level();
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Rq_Element ra((*ans.params).FFTD(),evaluation,evaluation);
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if (lev==0) { ra.lower_level(); }
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ra.from(a.get_iterator());
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ans.mul(c, ra);
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}
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void Ciphertext::mul(const Ciphertext& c, const Rq_Element& ra)
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{
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if (params!=c.params) { throw params_mismatch(); }
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pk_id = c.pk_id;
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::mul(cc0,ra,c.cc0);
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::mul(cc1,ra,c.cc1);
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}
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void Ciphertext::add(octetStream& os, int)
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{
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Ciphertext tmp(*params);
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tmp.unpack(os);
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*this += tmp;
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}
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void Ciphertext::rerandomize(const FHE_PK& pk)
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{
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Rq_Element tmp(*params);
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SeededPRNG G;
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vector<FFT_Data::S> r(params->FFTD()[0].phi_m());
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bigint p = pk.p();
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assert(p != 0);
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for (auto& x : r)
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{
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G.get(x, params->p0().numBits() - p.numBits() - 1);
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x *= p;
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}
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tmp.from(r, 0);
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Scale();
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cc0 += tmp;
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auto zero = pk.encrypt(*params);
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zero.Scale(pk.p());
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*this += zero;
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}
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template void mul(Ciphertext& ans,const Plaintext<gfp,FFT_Data,bigint>& a,const Ciphertext& c);
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template void mul(Ciphertext& ans, const Plaintext<gf2n_short, P2Data, int>& a,
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const Ciphertext& c);
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