Function mul

FHE/Ciphertext.cpp:60–90

void mul(Ciphertext& ans,const Ciphertext& c0,const Ciphertext& c1,
         const FHE_PK& pk)
{
  CODE_LOCATION_NO_SCOPE

  if (c0.params!=c1.params)  { throw params_mismatch(); }
  if (ans.params!=c1.params) { throw params_mismatch(); }

  // Switch Modulus for c0 and c1 down to level 0
  Ciphertext cc0=c0,cc1=c1;
  cc0.Scale(pk.p()); cc1.Scale(pk.p());
  
  // Now do the multiply
  auto d0 = cc0.cc0 * cc1.cc0;
  auto d1 = cc0.cc0 * cc1.cc1 + cc0.cc1 * cc1.cc0;
  auto d2 = cc0.cc1 * cc1.cc1;
  d2.negate(); 

  // Now do the switch key
  d2.raise_level();
  d0.mul_by_p1();
  auto t =  pk.bs()* d2;
  add(d0,d0,t);

  d1.mul_by_p1();
  mul(t,pk.as(),d2);
  add(d1,d1,t);

  ans.set(d0, d1, check_pk_id(c0.pk_id, c1.pk_id));
  ans.Scale(pk.p());
}


template<class T,class FD,class S>