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162 lines
3.6 KiB
C++
162 lines
3.6 KiB
C++
// (C) 2018 University of Bristol. See License.txt
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#include "Ciphertext.h"
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#include "Exceptions/Exceptions.h"
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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 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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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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Rq_Element d0,d1,d2;
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mul(d0,cc0.cc0,cc1.cc0);
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mul(d1,cc0.cc0,cc1.cc1);
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mul(d2,cc0.cc1,cc1.cc0);
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add(d1,d1,d2);
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mul(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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Rq_Element t;
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d0.mul_by_p1();
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mul(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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istream& operator>>(istream& s, Ciphertext& c)
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{
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int ch=s.get();
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while (isspace(ch))
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{ ch = s.get(); }
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if (ch != '[')
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{ throw IO_Error("Bad Ring_Element input: no '['"); }
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s >> c.pk_id;
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s >> c.cc0;
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ch=s.get();
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while (isspace(ch))
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{ ch = s.get(); }
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if (ch != ',')
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{ throw IO_Error("Bad Ring_Element input: no ','"); }
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s >> c.cc1;
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ch=s.get();
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while (isspace(ch))
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{ ch = s.get(); }
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if (ch != ']')
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{ throw IO_Error("Bad Ring_Element input: no ']'"); }
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return s;
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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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const vector<S>& aa=a.get_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_vec(aa);
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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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template <>
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void Ciphertext::add<0>(octetStream& os)
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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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template <>
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void Ciphertext::add<2>(octetStream& os)
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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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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<gfp,PPData,bigint>& a,const Ciphertext& c);
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template void mul(Ciphertext& ans,const Plaintext<gf2n_short,P2Data,int>& a,const Ciphertext& c);
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