Files
MP-SPDZ/FHE/P2Data.cpp
2022-05-27 14:20:31 +02:00

132 lines
3.0 KiB
C++

#include "FHE/P2Data.h"
#include "Math/Setup.h"
#include "Math/fixint.h"
#include <fstream>
void P2Data::forward(vector<poly_type>& ans,const vector<gf2n_short>& a) const
{
int n=gf2n_short::degree();
BitVector bv(A.size());
ans.resize(A.size());
for (int i=0; i<slots; i++)
{ word rep=a[i].get();
for (int j=0; j<n && rep!=0; j++)
{ if ((rep&1)==1)
{ int jj=i*n+j;
bv.add(A[jj]);
}
rep>>=1;
}
}
for (size_t i = 0; i < bv.size(); i++)
ans[i] = bv.get_bit(i);
}
void P2Data::backward(vector<gf2n_short>& ans,const vector<poly_type>& a) const
{
int n=gf2n_short::degree();
BitVector bv(a.size());
for (size_t i = 0; i < a.size(); i++)
bv.set_bit(i, a[i].get_limb(0));
ans.resize(slots);
word y;
for (int i=0; i<slots; i++)
{ y=0;
for (int j=0; j<n; j++)
{ y<<=1;
int ii = i * n + n - 1 - j;
y ^= (Ai[ii] & bv).parity();
}
ans[i] = (y);
}
}
void P2Data::check_dimensions() const
{
// cout << "degree: " << gf2n_short::degree() << endl;
// cout << "slots: " << slots << endl;
// cout << "A: " << A.size() << "x" << A[0].size() << endl;
// cout << "Ai: " << Ai.size() << "x" << Ai[0].size() << endl;
if (A.size() != Ai.size())
throw runtime_error("forward and backward mapping dimensions mismatch");
if (A.size() != A.at(0).size())
throw runtime_error("forward mapping not square");
if (Ai.size() != Ai.at(0).size())
throw runtime_error("backward mapping not square");
if ((int)A.at(0).size() != slots * gf2n_short::degree())
throw runtime_error(
"mapping dimension incorrect: " + to_string(A.at(0).size())
+ " != " + to_string(slots) + " * "
+ to_string(gf2n_short::degree()));
}
bool P2Data::operator!=(const P2Data& other) const
{
return slots != other.slots or A != other.A or Ai != other.Ai;
}
void P2Data::hash(octetStream& o) const
{
check_dimensions();
o.store(gf2n_short::degree());
o.store(slots);
A.hash(o);
Ai.hash(o);
}
void P2Data::pack(octetStream& o) const
{
check_dimensions();
o.store(gf2n_short::degree());
o.store(slots);
A.pack(o);
Ai.pack(o);
o.store_int(0xdeadbeef1, 8);
}
void P2Data::unpack(octetStream& o)
{
int degree;
o.get(degree);
gf2n_short::init_field(degree);
o.get(slots);
A.unpack(o);
Ai.unpack(o);
if (o.get_int(8) != 0xdeadbeef1)
throw runtime_error("P2Data serialization incorrect");
check_dimensions();
}
string get_filename(const Ring& Rg)
{
return (string) PREP_DIR + "P2D-" + to_string(gf2n_short::degree()) + "x"
+ to_string(Rg.phi_m() / gf2n_short::degree());
}
void P2Data::load(const Ring& Rg)
{
string filename = get_filename(Rg);
cout << "Loading from " << filename << endl;
ifstream s(filename);
octetStream os;
os.input(s);
unpack(os);
}
void P2Data::store(const Ring& Rg) const
{
string filename = get_filename(Rg);
cout << "Storing in " << filename << endl;
ofstream s(filename);
octetStream os;
pack(os);
os.output(s);
}