message: Adding random value c
diff: @@ -262,14 +262,17 @@ bool SigmaPlusVerifier<Exponent, GroupElement>::abcd_checks(
  const SigmaPlusProof<Exponent, GroupElement>& proof,
  const Exponent& x,
  const std::vector<Exponent>& f_) const {
  + Exponent c;
  + c.randomize();
  +
  std::vector<Exponent> f_plus_f_prime;
  f_plus_f_prime.reserve(f_.size());
  for(std::size_t i = 0; i < f_.size(); i++)
  - f_plus_f_prime.emplace_back(f_[i] + f_[i] * (x - f_[i]));
  + f_plus_f_prime.emplace_back(f_[i] * c + f_[i] * (x - f_[i]));
  GroupElement right;
  - LelantusPrimitives<Exponent, GroupElement>::commit(g_, h_, f_plus_f_prime, proof.ZA_ + proof.ZC_, right);
  - if((proof.B_ * x + proof.A_ + proof.C_ * x + proof.D_) != right)
  + LelantusPrimitives<Exponent, GroupElement>::commit(g_, h_, f_plus_f_prime, proof.ZA_ * c + proof.ZC_, right);
  + if(((proof.B_ * x + proof.A_) * c + proof.C_ * x + proof.D_) != right)
  return false;
  return true;
  }
  