/**
* @brief Extract coefficients from ciphertext polynomial
* @param coeffs extracted coefficients
* @param ctxt ciphertext
* @param n extract "n" lowest degree coefficients
*/
void extractCoeffs(EncryptedArray& ea, vector<Ctxt>& coeffs, Ctxt& ctxt, long n) {
long d = ea.getDegree();
if (d < n) n = d;
coeffs.clear();
vector<Ctxt> conj;
for (int coeff = 0; coeff < n; ++coeff) {
vector<ZZX> LM(d);
LM[coeff] = ZZX(0, 1);
// "building" the linearized-polynomial coefficients
vector<ZZX> C(d);
ea.buildLinPolyCoeffs(C, LM);
coeffs.push_back(ctxt);
applyLinPoly1(ea, coeffs[coeff], C, conj);
}
}
void TestIt(long R, long p, long r, long d, long c, long k, long w,
long L, long m)
{
cerr << "\n\n******** TestIt: R=" << R
<< ", p=" << p
<< ", r=" << r
<< ", d=" << d
<< ", c=" << c
<< ", k=" << k
<< ", w=" << w
<< ", L=" << L
<< ", m=" << m
<< endl;
FHEcontext context(m, p, r);
buildModChain(context, L, c);
// context.lazy = false;
if (context.lazy)
cerr << "LAZY REDUCTIONS\n";
else
cerr << "NON-LAZY REDUCTIONS\n";
context.zMStar.printout();
cerr << endl;
#ifdef DEBUG
cerr << context << endl;
#endif
FHESecKey secretKey(context);
const FHEPubKey& publicKey = secretKey;
secretKey.GenSecKey(w); // A Hamming-weight-w secret key
ZZX G;
if (d == 0) {
G = context.alMod.getFactorsOverZZ()[0];
d = deg(G);
}
else
G = makeIrredPoly(p, d);
cerr << "G = " << G << "\n";
cerr << "generating key-switching matrices... ";
addSome1DMatrices(secretKey); // compute key-switching matrices that we need
addFrbMatrices(secretKey); // compute key-switching matrices that we need
cerr << "done\n";
cerr << "computing masks and tables for rotation...";
EncryptedArray ea(context, G);
cerr << "done\n";
long nslots = ea.size();
// L selects even coefficients
vector<ZZX> LM(d);
for (long j = 0; j < d; j++)
if (j % 2 == 0) LM[j] = ZZX(j, 1);
vector<ZZX> C;
ea.buildLinPolyCoeffs(C, LM);
PlaintextArray p0(ea);
p0.random();
Ctxt c0(publicKey);
ea.encrypt(c0, publicKey, p0);
Ctxt res(c0);
applyLinPoly1(ea, res, C);
PlaintextArray pp0(ea);
ea.decrypt(res, secretKey, pp0);
p0.print(cout); cout << "\n";
pp0.print(cout); cout << "\n";
}
