recryption.h

/* 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.
 */
#ifndef HELIB_RECRYPTION_H
#define HELIB_RECRYPTION_H
 
#include <helib/NumbTh.h>
 
namespace helib {
 
extern long thinRecrypt_initial_level;
extern long fhe_force_chen_han;
extern long printFlag;
 
class PAlgebraMod;
class EncryptedArray;
class EvalMap;
class ThinEvalMap;
class PowerfulDCRT;
class Context;
class PubKey;
 
class RecryptData
{
public:
  static constexpr long defSkHwt = 100;
 
  NTL::Vec<long> mvec; 
 
  long e, ePrime;
 
  long skHwt;
 
  std::shared_ptr<const PAlgebraMod> alMod;
 
  std::shared_ptr<const EncryptedArray> ea;
 
  bool build_cache;
 
  std::shared_ptr<const EvalMap> firstMap, secondMap;
 
  std::shared_ptr<const PowerfulDCRT> p2dConv;
 
  std::vector<NTL::ZZX> unpackSlotEncoding;
 
  RecryptData()
  {
    skHwt = 0;
    e = ePrime = 0;
    build_cache = false;
  }
 
  void init(const Context& context,
            const NTL::Vec<long>& mvec_,
            bool enableThick, /*init linear transforms for non-thin*/
            long t = 0 /*min Hwt for sk*/,
            bool build_cache = false,
            bool minimal = false);
 
  bool operator==(const RecryptData& other) const;
  bool operator!=(const RecryptData& other) const
  {
    return !(operator==(other));
  }
 
  static long setAE(long& e, long& ePrime, const Context& context, long t = 0);
};
 
class ThinRecryptData : public RecryptData
{
public:
  std::shared_ptr<const ThinEvalMap> coeffToSlot, slotToCoeff;
 
  void init(const Context& context,
            const NTL::Vec<long>& mvec_,
            bool alsoThick, /*init linear transforms also for non-thin*/
            long t = 0 /*min Hwt for sk*/,
            bool build_cache = false,
            bool minimal = false);
};
 
#define HELIB_MIN_CAP_FRAC (2.0 / 3.0)
// Used in calculation of "min capacity".
// This could be set to 1.0, but just to be on the safe side,
// it is set to 2/3.  If we did set it to 1, the min capacity
// would increase by less than 6/10 of a bit.
 
} // namespace helib
 
#endif // HELIB_RECRYPTION_H