text: //#define DBG
  // Copyright (c) 2016, InSPa Research Labs
  //
  // Author: Shen Noether <shen.noether@gmx.com>
  //
  // All rights reserved.
  //
  // Redistribution and use in source and binary forms, with or without modification, are
  // permitted provided that the following conditions are met:
  //
  // 1. Redistributions of source code must retain the above copyright notice, this list of
  //    conditions and the following disclaimer.
  //
  // 2. Redistributions in binary form must reproduce the above copyright notice, this list
  //    of conditions and the following disclaimer in the documentation and/or other
  //    materials provided with the distribution.
  //
  // 3. Neither the name of the copyright holder nor the names of its contributors may be
  //    used to endorse or promote products derived from this software without specific
  //    prior written permission.
  //
  // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
  // EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
  // MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
  // THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  // PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  // INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
  // STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
  // THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  
  #pragma once
  
  #ifndef RCTOPS_H
  #define RCTOPS_H
  
  #include <cstddef>
  #include <tuple>
  
  #include "crypto/generic-ops.h"
  
  extern "C" {
  #include "crypto/random.h"
  #include "crypto/keccak.h"
  #include "rctCryptoOps.h"
  }
  #include "crypto/crypto.h"
  
  #include "rctTypes.h"
  
  //Define this flag when debugging to get additional info on the console
  #ifdef DBG
  #define DP(x) dp(x)
  #else
  #define DP(x)
  #endif
  
  namespace rct {
  
      //Various key initialization functions
  
      static const key Z = { {0x00, 0x00, 0x00,0x00 , 0x00, 0x00, 0x00,0x00 , 0x00, 0x00, 0x00,0x00 , 0x00, 0x00, 0x00,0x00 , 0x00, 0x00, 0x00,0x00 , 0x00, 0x00, 0x00,0x00 , 0x00, 0x00, 0x00,0x00 , 0x00, 0x00, 0x00,0x00  } };
      static const key I = { {0x01, 0x00, 0x00,0x00 , 0x00, 0x00, 0x00,0x00 , 0x00, 0x00, 0x00,0x00 , 0x00, 0x00, 0x00,0x00 , 0x00, 0x00, 0x00,0x00 , 0x00, 0x00, 0x00,0x00 , 0x00, 0x00, 0x00,0x00 , 0x00, 0x00, 0x00,0x00  } };
      static const key L = { {0xed, 0xd3, 0xf5, 0x5c, 0x1a, 0x63, 0x12, 0x58, 0xd6, 0x9c, 0xf7, 0xa2, 0xde, 0xf9, 0xde, 0x14, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x10 } };
      static const key G = { {0x58, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66 } };
  
      //Creates a zero scalar
      inline key zero() { return Z; }
      inline void zero(key &z) { memset(&z, 0, 32); }
      //Creates a zero elliptic curve point
      inline key identity() { return I; }
      inline void identity(key &Id) { memcpy(&Id, &I, 32); }
      //Creates a key equal to the curve order
      inline key curveOrder() { return L; }
      inline void curveOrder(key &l) { l = L; }
      //copies a scalar or point
      inline void copy(key &AA, const key &A) { memcpy(&AA, &A, 32); }
      inline key copy(const key & A) { key AA; memcpy(&AA, &A, 32); return AA; }
  
      //initializes a key matrix;
      //first parameter is rows, 
      //second is columns
      keyM keyMInit(size_t rows, size_t cols);
  
      //Various key generation functions        
  
      //generates a random scalar which can be used as a secret key or mask
      key skGen();
      void skGen(key &);
      
      //generates a vector of secret keys of size "int"
      keyV skvGen(size_t rows );
      
      //generates a random curve point (for testing)
      key pkGen();
      //generates a random secret and corresponding public key
      void skpkGen(key &sk, key &pk);
      std::tuple<key, key> skpkGen();
      //generates a <secret , public> / Pedersen commitment to the amount
      std::tuple<ctkey, ctkey> ctskpkGen(xmr_amount amount);
      //generates C =aG + bH from b, a is random
      void genC(key & C, const key & a, xmr_amount amount);
      //this one is mainly for testing, can take arbitrary amounts..
      std::tuple<ctkey, ctkey> ctskpkGen(const key &bH);
      // make a pedersen commitment with given key
      key commit(xmr_amount amount, const key &mask);
      // make a pedersen commitment with zero key
      key zeroCommit(xmr_amount amount);
      //generates a random uint long long
      xmr_amount randXmrAmount(xmr_amount upperlimit);
  
      //Scalar multiplications of curve points        
  
      //does a * G where a is a scalar and G is the curve basepoint
      void scalarmultBase(key & aG, const key &a);
      key scalarmultBase(const key & a);
      //does a * P where a is a scalar and P is an arbitrary point
      void scalarmultKey(key &aP, const key &P, const key &a);
      key scalarmultKey(const key &P, const key &a);
      //Computes aH where H= toPoint(cn_fast_hash(G)), G the basepoint
      key scalarmultH(const key & a);
  
      //Curve addition / subtractions
  
      //for curve points: AB = A + B
      void addKeys(key &AB, const key &A, const key &B);
      rct::key addKeys(const key &A, const key &B);
      //aGB = aG + B where a is a scalar, G is the basepoint, and B is a point
      void addKeys1(key &aGB, const key &a, const key & B);
      //aGbB = aG + bB where a, b are scalars, G is the basepoint and B is a point
      void addKeys2(key &aGbB, const key &a, const key &b, const key &B);
      //Does some precomputation to make addKeys3 more efficient
      // input B a curve point and output a ge_dsmp which has precomputation applied
      void precomp(ge_dsmp rv, const key &B);
      //aAbB = a*A + b*B where a, b are scalars, A, B are curve points
      //B must be input after applying "precomp"
      void addKeys3(key &aAbB, const key &a, const key &A, const key &b, const ge_dsmp B);
      void addKeys3(key &aAbB, const key &a, const ge_dsmp A, const key &b, const ge_dsmp B);
      //AB = A - B where A, B are curve points
      void subKeys(key &AB, const key &A, const  key &B);
      //checks if A, B are equal as curve points
      bool equalKeys(const key & A, const key & B);
  
      //Hashing - cn_fast_hash
      //be careful these are also in crypto namespace
      //cn_fast_hash for arbitrary l multiples of 32 bytes 
      void cn_fast_hash(key &hash, const void * data, const size_t l);
      void hash_to_scalar(key &hash, const void * data, const size_t l);
      //cn_fast_hash for a 32 byte key
      void cn_fast_hash(key &hash, const key &in);
      void hash_to_scalar(key &hash, const key &in);
      //cn_fast_hash for a 32 byte key
      key cn_fast_hash(const key &in);
      key hash_to_scalar(const key &in);
      //for mg sigs
      key cn_fast_hash128(const void * in);
      key hash_to_scalar128(const void * in);
      key cn_fast_hash(const ctkeyV &PC);
      key hash_to_scalar(const ctkeyV &PC);
      //for mg sigs 
      key cn_fast_hash(const keyV &keys);
      key hash_to_scalar(const keyV &keys);
      //for ANSL
      key cn_fast_hash(const key64 keys);
      key hash_to_scalar(const key64 keys);
  
      //returns hashToPoint as described in https://github.com/ShenNoether/ge_fromfe_writeup 
      key hashToPointSimple(const key &in);
      key hashToPoint(const key &in);
      void hashToPoint(key &out, const key &in);
  
      //sums a vector of curve points (for scalars use sc_add)
      void sumKeys(key & Csum, const key &Cis);
  
      //Elliptic Curve Diffie Helman: encodes and decodes the amount b and mask a
      // where C= aG + bH
      void ecdhEncode(ecdhTuple & unmasked, const key & sharedSec);
      void ecdhDecode(ecdhTuple & masked, const key & sharedSec);
  }
  #endif  /* RCTOPS_H */
  