void decryptAndPrint(ostream& s, const Ctxt& ctxt, const FHESecKey& sk,
const EncryptedArray& ea, long flags)
{
const FHEcontext& context = ctxt.getContext();
xdouble noiseEst = sqrt(ctxt.getNoiseVar());
xdouble modulus = xexp(context.logOfProduct(ctxt.getPrimeSet()));
vector<ZZX> ptxt;
ZZX p, pp;
sk.Decrypt(p, ctxt, pp);
s << "plaintext space mod "<<ctxt.getPtxtSpace()
<< ", level="<<ctxt.findBaseLevel()
<< ", \n |noise|=q*" << (coeffsL2Norm(pp)/modulus)
<< ", |noiseEst|=q*" << (noiseEst/modulus)
<<endl;
if (flags & FLAG_PRINT_ZZX) {
s << " before mod-p reduction=";
printZZX(s,pp) <<endl;
}
if (flags & FLAG_PRINT_POLY) {
s << " after mod-p reduction=";
printZZX(s,p) <<endl;
}
if (flags & FLAG_PRINT_VEC) {
ea.decode(ptxt, p);
if (ea.getAlMod().getTag() == PA_zz_p_tag
&& ctxt.getPtxtSpace() != ea.getAlMod().getPPowR()) {
long g = GCD(ctxt.getPtxtSpace(), ea.getAlMod().getPPowR());
for (long i=0; i<ea.size(); i++)
PolyRed(ptxt[i], g, true);
}
s << " decoded to ";
if (deg(p) < 40) // just pring the whole thing
s << ptxt << endl;
else if (ptxt.size()==1) // a single slot
printZZX(s, ptxt[0]) <<endl;
else { // print first and last slots
printZZX(s, ptxt[0],20) << "--";
printZZX(s, ptxt[ptxt.size()-1], 20) <<endl;
}
}
}
void checkCiphertext(const Ctxt& ctxt, const ZZX& ptxt, const FHESecKey& sk)
{
const FHEcontext& context = ctxt.getContext();
/*
IndexSet base = baseSetOf(ctxt);
double addedNoise = log(ctxt.modSwitchAddedNoiseVar());
Ctxt tmp = ctxt;
tmp.modDownToSet(base);
double totalNoise = log(tmp.getNoiseVar());
cout << " @@@ log(added-noise)="<<addedNoise
<< ", log(total-noise)="<<totalNoise<<endl;
*/
cout << " ln(q)="<< context.logOfProduct(ctxt.getPrimeSet())
<< ", ln(nVar)/2="<< log(ctxt.getNoiseVar())/2;
// << ", ln(nMag)="<< log(ctxt.getNoiseMag());
ZZX res;
// sk.Decrypt(res, ctxt);
ZZX f;
sk.Decrypt(res, ctxt, f);
cout << ", ln(mxPtxtCoef)=" << log(largestCoeff(f));
// ensure we reduce the same way on both
PolyRed((ZZX&)res,res,ctxt.getPtxtSpace(),true);
PolyRed((ZZX&)ptxt,ptxt,ctxt.getPtxtSpace(),true);
if (res != ptxt) {
cout << ", failed\n";
for (long i=0; i<=deg(ptxt); i++) if (coeff(res,i)!=coeff(ptxt,i)) {
cout << "first mismatch in coeff "<<i<<": "
<< coeff(res,i)<<"!="<<coeff(ptxt,i)<<"\n";
break;
}
cout << "Timing information:\n";
printAllTimers();
cout << "\n";
exit(0);
}
else cout << ", succeeded\n";
}
void adjustLevelForMult(Ctxt& c1, const char name1[], const ZZX& p1,
Ctxt& c2, const char name2[], const ZZX& p2,
const FHESecKey& sk)
{
const FHEcontext& context = c1.getContext();
// The highest possible level for this multiplication is the
// intersection of the two primeSets, without the special primes.
IndexSet primes = c1.getPrimeSet() & c2.getPrimeSet();
primes.remove(context.specialPrimes);
assert (!empty(primes));
// double phim = (double) context.zMstar.phiM();
// double factor = c_m*sqrt(log(phim))*4;
xdouble n1,n2,d1,d2;
xdouble dvar1 = c1.modSwitchAddedNoiseVar();
xdouble dvar2 = c2.modSwitchAddedNoiseVar();
// xdouble dmag1 = c1.modSwitchAddedNoiseMag(c_m);
// xdouble dmag2 = c2.modSwitchAddedNoiseMag(c_m);
// cout << " ** log(dvar1)=" << log(dvar1)
// << ", log(dvar2)=" << log(dvar2) <<endl;
double logF1, logF2;
xdouble n1var, n2var, modSize; // n1mag, n2mag,
// init to large number
xdouble noiseVarRatio=xexp(2*(context.logOfProduct(context.ctxtPrimes)
+ context.logOfProduct(context.specialPrimes)));
// xdouble noiseMagRatio=noiseVarRatio;
// Find the level that minimizes the noise-to-modulus ratio
bool oneLevelMore = false;
for (IndexSet levelDown = primes;
!empty(levelDown); levelDown.remove(levelDown.last())) {
// compute noise variane/magnitude after mod-switchign to this level
logF1 = context.logOfProduct(c1.getPrimeSet() / levelDown);
n1var = c1.getNoiseVar()/xexp(2*logF1);
logF2 = context.logOfProduct(c2.getPrimeSet() / levelDown);
n2var = c2.getNoiseVar()/xexp(2*logF2);
// compute modulus/noise ratio at this level
modSize = xexp(context.logOfProduct(levelDown));
xdouble nextNoiseVarRatio = sqrt((n1var+dvar1)*(n2var+dvar2))/modSize;
if (nextNoiseVarRatio < 2*noiseVarRatio || oneLevelMore) {
noiseVarRatio = nextNoiseVarRatio;
primes = levelDown; // record the currently best prime set
n1 = n1var; d1=dvar1; n2 = n2var; d2=dvar2;
}
oneLevelMore = (n1var > dvar1 || n2var > dvar2);
}
if (primes < c1.getPrimeSet()) {
cout << " ** " << c1.getPrimeSet()<<"=>"<<primes << endl;
cout << " n1var="<<n1<<", d1var="<<d1<<endl;;
c1.modDownToSet(primes);
cout << name1 << ".mDown:"; checkCiphertext(c1, p1, sk);
}
if (primes < c2.getPrimeSet()) {
cout << " ** " << c2.getPrimeSet()<<"=>"<<primes << endl;
cout << " n2var="<<n2<<", d2var="<<d2<<endl;;
c2.modDownToSet(primes);
cout << name2 << ".mDown:"; checkCiphertext(c2, p2, sk);
}
}
