C++ EncryptedArray::getDegree方法代码示例

// Use packed bootstrapping, so we can bootstrap all in just one go.
void packedRecrypt(const CtPtrs& cPtrs,
                   const std::vector<zzX>& unpackConsts,
                   const EncryptedArray& ea)
{
  FHEPubKey& pKey = (FHEPubKey&)cPtrs[0]->getPubKey();

  // Allocate temporary ciphertexts for the recryption
  int nPacked = divc(cPtrs.size(), ea.getDegree()); // ceil(totoalNum/d)
  std::vector<Ctxt> cts(nPacked, Ctxt(pKey));

  repack(CtPtrs_vectorCt(cts), cPtrs, ea);  // pack ciphertexts
  //  cout << "@"<< lsize(cts)<<std::flush;
  for (Ctxt& c: cts) {     // then recrypt them
    c.reducePtxtSpace(2);  // we only have recryption data for binary ctxt
#ifdef DEBUG_PRINTOUT
    ZZX ptxt;
    decryptAndPrint((cout<<"  before recryption "), c, *dbgKey, *dbgEa);
    dbgKey->Decrypt(ptxt, c);
    c.DummyEncrypt(ptxt);
    decryptAndPrint((cout<<"  after recryption "), c, *dbgKey, *dbgEa);
#else
    pKey.reCrypt(c);
#endif
  }
  unpack(cPtrs, CtPtrs_vectorCt(cts), ea, unpackConsts);
}

NTL_CLIENT
#include "FHE.h"
#include "timing.h"
#include "EncryptedArray.h"

#include <cstdio>

// Map all non-zero slots to 1, leaving zero slots as zero.
// Assumes that r=1, and that all the slot contain elements from GF(p^d).
//
// We compute x^{p^d-1} = x^{(1+p+...+p^{d-1})*(p-1)} by setting y=x^{p-1}
// and then outputting y * y^p * ... * y^{p^{d-1}}, with exponentiation to
// powers of p done via Frobenius.

// FIXME: the computation of the "norm" y * y^p * ... * y^{p^{d-1}}
// can be done using O(log d) automorphisms, rather than O(d).

void mapTo01(const EncryptedArray& ea, Ctxt& ctxt)
{
  long p = ctxt.getPtxtSpace();
  if (p != ea.getPAlgebra().getP()) // ptxt space is p^r for r>1
    throw helib::LogicError("mapTo01 not implemented for r>1");

  if (p>2)
    ctxt.power(p-1); // set y = x^{p-1}

  long d = ea.getDegree();
  if (d>1) { // compute the product of the d automorphisms
    std::vector<Ctxt> v(d, ctxt);
    for (long i=1; i<d; i++)
      v[i].frobeniusAutomorph(i);
    totalProduct(ctxt, v);
  }
}

// incrementalZeroTest sets each res[i], for i=0..n-1, to
// a ciphertext in which each slot is 0 or 1 according
// to whether or not bits 0..i of corresponding slot in ctxt
// is zero (1 if not zero, 0 if zero).
// It is assumed that res and each res[i] is already initialized
// by the caller.
// Complexity: O(d + n log d) smart automorphisms
//             O(n d) 
void incrementalZeroTest(Ctxt* res[], const EncryptedArray& ea,
			 const Ctxt& ctxt, long n)
{
  FHE_TIMER_START;
  long nslots = ea.size();
  long d = ea.getDegree();

  // compute linearized polynomial coefficients

  vector< vector<ZZX> > Coeff;
  Coeff.resize(n);

  for (long i = 0; i < n; i++) {
    // coeffients for mask on bits 0..i
    // L[j] = X^j for j = 0..i, L[j] = 0 for j = i+1..d-1

    vector<ZZX> L;
    L.resize(d);

    for (long j = 0; j <= i; j++) 
      SetCoeff(L[j], j);

    vector<ZZX> C;

    ea.buildLinPolyCoeffs(C, L);

    Coeff[i].resize(d);
    for (long j = 0; j < d; j++) {
      // Coeff[i][j] = to the encoding that has C[j] in all slots
      // FIXME: maybe encrtpted array should have this functionality
      //        built in
      vector<ZZX> T;
      T.resize(nslots);
      for (long s = 0; s < nslots; s++) T[s] = C[j];
      ea.encode(Coeff[i][j], T);
    }
  }

  vector<Ctxt> Conj(d, ctxt);
  // initialize Cong[j] to ctxt^{2^j}
  for (long j = 0; j < d; j++) {
    Conj[j].smartAutomorph(1L << j);
  }

  for (long i = 0; i < n; i++) {
    res[i]->clear();
    for (long j = 0; j < d; j++) {
      Ctxt tmp = Conj[j];
      tmp.multByConstant(Coeff[i][j]);
      *res[i] += tmp;
    }

    // *res[i] now has 0..i in each slot
    // next, we raise to the power 2^d-1

    fastPower(*res[i], d);
  }
  FHE_TIMER_STOP;
}

// Apply the same linear transformation to all the slots.
// C is the output of ea.buildLinPolyCoeffs
void applyLinPoly1(const EncryptedArray& ea, Ctxt& ctxt, const vector<ZZX>& C)
{
  assert(&ea.getContext() == &ctxt.getContext());
  long d = ea.getDegree();
  assert(d == lsize(C));

  long nslots = ea.size();

  vector<ZZX> encodedC(d);
  for (long j = 0; j < d; j++) {
    vector<ZZX> v(nslots);
    for (long i = 0; i < nslots; i++) v[i] = C[j];
    ea.encode(encodedC[j], v);
  }

  applyLinPolyLL(ctxt, encodedC, ea.getDegree());
}

/**
 * @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);
  }
}