/*
 *
 *  Embedded Linux library
 *
 *  Copyright (C) 2018 Intel Corporation. All rights reserved.
 *
 *  This library is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU Lesser General Public
 *  License as published by the Free Software Foundation; either
 *  version 2.1 of the License, or (at your option) any later version.
 *
 *  This library is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *  Lesser General Public License for more details.
 *
 *  You should have received a copy of the GNU Lesser General Public
 *  License along with this library; if not, write to the Free Software
 *  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 *
 */

#ifndef __ELL_ECC_H
#define __ELL_ECC_H

#ifdef __cplusplus
extern "C" {
#endif

#include <sys/types.h> // for ssize_t

#define L_ECC_MAX_DIGITS 6
#define L_ECC_SCALAR_MAX_BYTES		L_ECC_MAX_DIGITS * 8
#define L_ECC_POINT_MAX_BYTES		L_ECC_SCALAR_MAX_BYTES * 2

struct l_ecc_curve;
struct l_ecc_point;
struct l_ecc_scalar;

enum l_ecc_point_type {
	L_ECC_POINT_TYPE_COMPLIANT = 0x01,
	L_ECC_POINT_TYPE_COMPRESSED_BIT0 = 0x02,
	L_ECC_POINT_TYPE_COMPRESSED_BIT1 = 0x03,
	L_ECC_POINT_TYPE_FULL = 0x04,
};

const struct l_ecc_curve *l_ecc_curve_get(const char *name);
const char *l_ecc_curve_get_name(const struct l_ecc_curve *curve);
size_t l_ecc_curve_get_scalar_bytes(const struct l_ecc_curve *curve);
const unsigned int *l_ecc_curve_get_supported_ike_groups(void);
const unsigned int *l_ecc_curve_get_supported_tls_groups(void);
const struct l_ecc_curve *l_ecc_curve_get_ike_group(unsigned int group);
const struct l_ecc_curve *l_ecc_curve_get_tls_group(unsigned int group);

struct l_ecc_point *l_ecc_point_new(const struct l_ecc_curve *curve);
struct l_ecc_point *l_ecc_point_from_data(const struct l_ecc_curve *curve,
					enum l_ecc_point_type type,
					const void *data, size_t len);

ssize_t l_ecc_point_get_x(const struct l_ecc_point *p, void *x, size_t xlen);
ssize_t l_ecc_point_get_data(const struct l_ecc_point *p, void *buf, size_t len);
void l_ecc_point_free(struct l_ecc_point *p);

struct l_ecc_scalar *l_ecc_scalar_new(const struct l_ecc_curve *curve,
						const void *buf, size_t len);
struct l_ecc_scalar *l_ecc_scalar_new_random(
					const struct l_ecc_curve *curve);
ssize_t l_ecc_scalar_get_data(const struct l_ecc_scalar *c, void *buf,
					size_t len);
void l_ecc_scalar_free(struct l_ecc_scalar *c);

/* Constant operations */
struct l_ecc_scalar *l_ecc_curve_get_order(const struct l_ecc_curve *curve);
bool l_ecc_scalar_add(struct l_ecc_scalar *ret, const struct l_ecc_scalar *a,
				const struct l_ecc_scalar *b,
				const struct l_ecc_scalar *mod);

/* Point operations */
bool l_ecc_point_multiply(struct l_ecc_point *ret,
				const struct l_ecc_scalar *scalar,
				const struct l_ecc_point *point);
bool l_ecc_point_add(struct l_ecc_point *ret, const struct l_ecc_point *a,
				const struct l_ecc_point *b);
bool l_ecc_point_inverse(struct l_ecc_point *p);

/* extra operations needed for SAE */
bool l_ecc_scalar_multiply(struct l_ecc_scalar *ret,
				const struct l_ecc_scalar *a,
				const struct l_ecc_scalar *b);
int l_ecc_scalar_legendre(struct l_ecc_scalar *value);
bool l_ecc_scalar_sum_x(struct l_ecc_scalar *ret, const struct l_ecc_scalar *x);

struct l_ecc_scalar *l_ecc_curve_get_prime(const struct l_ecc_curve *curve);

bool l_ecc_scalars_are_equal(const struct l_ecc_scalar *a,
				const struct l_ecc_scalar *b);

bool l_ecc_points_are_equal(const struct l_ecc_point *a,
				const struct l_ecc_point *b);

#ifdef __cplusplus
}
#endif

#endif /* __ELL_ECC_H */