Method fake

FHEOffline/DistKeyGen.cpp:29–93

void DistKeyGen::fake(FHE_PK& pk, vector<FHE_SK>& sks, const bigint& p, int nparties)
{
    vector<DistKeyGen> dkgs(nparties, {pk.get_params(), p});
    sks.resize(nparties, {pk.get_params(), p});
    vector<Rq_Element> secrets(nparties, pk.get_params());
    PRNG G;
    G.ReSeed();
    for (int i = 0; i < nparties; i++)
        dkgs[i].Gen_Random_Data(G);

    Rq_Element a = dkgs[0].a;
    for (size_t i = 1; i < dkgs.size(); i++)
        a += dkgs[i].a;
    for (int i = 0; i < nparties; i++)
    {
        dkgs[i].a = a;
        dkgs[i].compute_b();
        secrets[i] = dkgs[i].secret;
    }

    Rq_Element b = dkgs[0].b;
    for (size_t i = 1; i < dkgs.size(); i++)
        b += dkgs[i].b;
    pk.check_noise(b - a * sum(secrets));
    for (int i = 0; i < nparties; i++)
    {
        dkgs[i].b = b;
        dkgs[i].compute_enc_dash();
        cout << "after enc_dash" << endl;
        pk.check_noise(dkgs[i].b - dkgs[i].a * sum(secrets));
    }

    Ciphertext enc_dash = dkgs[0].enc_dash;
    for (size_t i = 1; i < dkgs.size(); i++)
        enc_dash += dkgs[i].enc_dash;
    for (int i = 0; i < nparties; i++)
    {
        dkgs[i].enc_dash = enc_dash;
        dkgs[i].compute_enc();
        cout << "after enc" << endl;
        pk.check_noise(dkgs[i].b - dkgs[i].a * sum(secrets));
    }

    Rq_Element s = sum(secrets);
    s.lower_level();
    FHE_SK sk(pk.get_params(), p);
    sk.assign(s);

    Ciphertext enc = dkgs[0].enc;
    for (size_t i = 1; i < dkgs.size(); i++)
        enc += dkgs[i].enc;
    for (int i = 0; i < nparties; i++)
    {
        dkgs[i].enc = enc;
        dkgs[i].check_equality(dkgs[0]);
        dkgs[i].finalize(pk, sks[i]);
        cout << "after finalize" << endl;
        pk.check_noise(dkgs[i].b - dkgs[i].a * sum(secrets));