/*
* Copyright (c) 2013-2020, The PurpleI2P Project
*
* This file is part of Purple i2pd project and licensed under BSD3
*
* See full license text in LICENSE file at top of project tree
*/

#ifndef ELLIGATOR_H__
#define ELLIGATOR_H__

#include <inttypes.h>
#include <memory>
#include <openssl/bn.h>

namespace i2p {
    namespace crypto {

        class Elligator2 {
        public:

            Elligator2();

            ~Elligator2();

            bool Encode(const uint8_t *key, uint8_t *encoded, bool highY = false, bool random = true) const;

            bool Decode(const uint8_t *encoded, uint8_t *key) const;

        private:

            void SquareRoot(const BIGNUM *x, BIGNUM *r, BN_CTX *ctx) const;

            int Legendre(const BIGNUM *a, BN_CTX *ctx) const; // a/p

        private:

            BIGNUM *p, *p38, *p12, *p14, *sqrtn1, *A, *nA, *u, *iu;
        };

        std::unique_ptr <Elligator2> &GetElligator();
    }
}

#endif