xref: /dports/security/helib/HElib-1.3.1/src/debugging.cpp

/* Copyright (C) 2012-2020 IBM Corp.
 * This program is Licensed under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance
 * with the License. You may obtain a copy of the License at
 *   http://www.apache.org/licenses/LICENSE-2.0
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License. See accompanying LICENSE file.
 */
// debugging.cpp - debugging utilities
#include <NTL/xdouble.h>
#include <helib/debugging.h>
#include <helib/norms.h>
#include <helib/Context.h>
#include <helib/Ctxt.h>
#include <helib/EncryptedArray.h>
//#include <helib/powerful.h>

namespace helib {

SecKey* dbgKey = nullptr;
std::shared_ptr<const EncryptedArray> dbgEa = nullptr;
NTL::ZZX dbg_ptxt;

// return the ratio between the real noise <sk,ct> and the estimated one
double realToEstimatedNoise(const Ctxt& ctxt, const SecKey& sk)
{
  NTL::xdouble noiseEst = ctxt.totalNoiseBound();
  NTL::xdouble actualNoise = embeddingLargestCoeff(ctxt, sk);

  return NTL::conv<double>(actualNoise / noiseEst);
}

double log2_realToEstimatedNoise(const Ctxt& ctxt, const SecKey& sk)
{
  NTL::xdouble noiseEst = ctxt.totalNoiseBound();
  NTL::xdouble actualNoise = embeddingLargestCoeff(ctxt, sk);

  return NTL::log(actualNoise / noiseEst) / std::log(2.0);
}

// check that real-to-estimated ratio is not too large, print warning otherwise
void checkNoise(const Ctxt& ctxt,
                const SecKey& sk,
                const std::string& msg,
                double thresh)
{
  double ratio;
  if ((ratio = realToEstimatedNoise(ctxt, sk)) > thresh) {
    std::cerr << "\n*** too much noise: " << msg << ": " << ratio << "\n";
  }
}

// Decrypt and find the l-infinity norm of the result in canonical embedding
NTL::xdouble embeddingLargestCoeff(const Ctxt& ctxt, const SecKey& sk)
{
  const Context& context = ctxt.getContext();
  NTL::ZZX p, pp;
  sk.Decrypt(p, ctxt, pp);
  return embeddingLargestCoeff(pp, context.zMStar);
}

void decryptAndPrint(std::ostream& s,
                     const Ctxt& ctxt,
                     const SecKey& sk,
                     const EncryptedArray& ea,
                     long flags)
{
  const Context& context = ctxt.getContext();
  std::vector<NTL::ZZX> ptxt;
  NTL::ZZX p, pp;
  sk.Decrypt(p, ctxt, pp);

  NTL::xdouble modulus = NTL::xexp(context.logOfProduct(ctxt.getPrimeSet()));
  NTL::xdouble actualNoise =
      embeddingLargestCoeff(pp, ctxt.getContext().zMStar);
  NTL::xdouble noiseEst = ctxt.totalNoiseBound();

  s << "plaintext space mod " << ctxt.getPtxtSpace()
    << ", capacity=" << ctxt.capacity() << ", \n           |noise|=q*"
    << (actualNoise / modulus) << ", |noiseBound|=q*" << (noiseEst / modulus);
  if (ctxt.isCKKS()) {
    s << ", \n           ratFactor=" << ctxt.getRatFactor()
      << ", ptxtMag=" << ctxt.getPtxtMag()
      << ", scaledErr=" << (actualNoise / ctxt.getRatFactor());
  }
  s << std::endl;

  if (flags & FLAG_PRINT_ZZX) {
    s << "   before mod-p reduction=";
    printZZX(s, pp) << std::endl;
  }
  if (flags & FLAG_PRINT_POLY) {
    s << "   after mod-p reduction=";
    printZZX(s, p) << std::endl;
  }
  if (flags & FLAG_PRINT_VEC) { // decode to a vector of ZZX
    ea.decode(ptxt, p);
    if (ea.getAlMod().getTag() == PA_zz_p_tag &&
        ctxt.getPtxtSpace() != ea.getAlMod().getPPowR()) {
      long g = NTL::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 print the whole thing
      s << ptxt << std::endl;
    else if (ptxt.size() == 1) // a single slot
      printZZX(s, ptxt[0]) << std::endl;
    else { // print first and last slots
      printZZX(s, ptxt[0], 20) << "--";
      printZZX(s, ptxt[ptxt.size() - 1], 20) << std::endl;
    }
  } else if (flags & FLAG_PRINT_DVEC) { // decode to a vector of doubles
    const EncryptedArrayCx& eacx = ea.getCx();
    std::vector<double> v;
    eacx.rawDecrypt(ctxt, sk, v);
    printVec(s << "           ", v, 20) << std::endl;
  } else if (flags & FLAG_PRINT_XVEC) { // decode to a vector of complex
    const EncryptedArrayCx& eacx = ea.getCx();
    std::vector<cx_double> v;
    eacx.rawDecrypt(ctxt, sk, v);
    printVec(s << "           ", v, 20) << std::endl;
  }
}

bool decryptAndCompare(const Ctxt& ctxt,
                       const SecKey& sk,
                       const EncryptedArray& ea,
                       const PlaintextArray& pa)
{
  PlaintextArray ppa(ea);
  ea.decrypt(ctxt, sk, ppa);

  return equals(ea, pa, ppa);
}

// Compute decryption with.without mod-q on a vector of ZZX'es,
// useful when debugging bootstrapping (after "raw mod-switch")
void rawDecrypt(NTL::ZZX& plaintxt,
                const std::vector<NTL::ZZX>& zzParts,
                const DoubleCRT& sKey,
                long q)
{
  // Set to zzParts[0] + sKey * zzParts[1] "over the integers"
  DoubleCRT ptxt = sKey;
  ptxt *= zzParts[1];
  ptxt += zzParts[0];

  // convert to coefficient representation
  ptxt.toPoly(plaintxt);

  if (q > 1)
    PolyRed(plaintxt, q, false /*reduce to [-q/2,1/2]*/);
}

void CheckCtxt(const Ctxt& c, const char* label)
{
  std::cerr << "  " << label << ", capacity=" << c.capacity();

  if (!c.isCKKS())
    std::cerr << ", p^r=" << c.getPtxtSpace();

  if (dbgKey) {
    double ratio = log2_realToEstimatedNoise(c, *dbgKey);
    std::cerr << ", log2(noise/bound)=" << ratio;
    if (ratio > 0)
      std::cerr << " BAD-BOUND";
  }

#if 0
  // This is not really a useful test

  if (dbgKey && c.getContext().isBootstrappable()) {
    Ctxt c1(c);
    //c1.dropSmallAndSpecialPrimes();

    const Context& context = c1.getContext();
    const RecryptData& rcData = context.rcData;
    const PAlgebra& palg = context.zMStar;

    NTL::ZZX p, pp;
    dbgKey->Decrypt(p, c1, pp);
    NTL::Vec<NTL::ZZ> powerful;
    rcData.p2dConv->ZZXtoPowerful(powerful, pp);

    NTL::ZZ q;
    q = context.productOfPrimes(c1.getPrimeSet());
    vecRed(powerful, powerful, q, false);

    NTL::ZZX pp_alt;
    rcData.p2dConv->powerfulToZZX(pp_alt, powerful);

    NTL::xdouble max_coeff = NTL::conv<NTL::xdouble>(largestCoeff(pp));
    NTL::xdouble max_pwrfl = NTL::conv<NTL::xdouble>(largestCoeff(powerful));
    NTL::xdouble max_canon = embeddingLargestCoeff(pp_alt, palg);
    double ratio = log(max_pwrfl/max_canon)/log(2.0);

    //cerr << ", max_coeff=" << max_coeff;
    //cerr << ", max_pwrfl=" << max_pwrfl;
    //cerr << ", max_canon=" << max_canon;
    std::cerr << ", log2(max_pwrfl/max_canon)=" << ratio;
    if (ratio > 0) std::cerr << " BAD-BOUND";
  }
#endif

  std::cerr << std::endl;
}

} // namespace helib