/*
 *  Copyright (C) 2017 - This file is part of libecc project
 *
 *  Authors:
 *      Ryad BENADJILA <ryadbenadjila@gmail.com>
 *      Arnaud EBALARD <arnaud.ebalard@ssi.gouv.fr>
 *      Jean-Pierre FLORI <jean-pierre.flori@ssi.gouv.fr>
 *
 *  Contributors:
 *      Nicolas VIVET <nicolas.vivet@ssi.gouv.fr>
 *      Karim KHALFALLAH <karim.khalfallah@ssi.gouv.fr>
 *
 *  This software is licensed under a dual BSD and GPL v2 license.
 *  See LICENSE file at the root folder of the project.
 */
#include <libecc/curves/ec_params.h>
#include <libecc/curves/curves.h>

/*
 * Initialize (already allocated) curve parameters structure pointed by
 * ec_params using value provided in remaining parameters. The function
 * returns 0 on success, -1 on error.
 */
int import_params(ec_params *out_params, const ec_str_params *in_str_params)
{
        nn tmp_p, tmp_p_bitlen, tmp_r, tmp_r_square, tmp_mpinv, tmp_p_shift;
        nn tmp_p_normalized, tmp_p_reciprocal, tmp_curve_order, tmp_order;
        nn tmp_order_bitlen, tmp_cofactor;
        fp tmp_a, tmp_b, tmp_gx, tmp_gy, tmp_gz;
        ec_curve_type curve_type;
        int ret;
        tmp_p.magic = tmp_r.magic = tmp_r_square.magic = tmp_mpinv.magic = WORD(0);
        tmp_p_shift.magic = tmp_p_normalized.magic = tmp_p_reciprocal.magic = WORD(0);
        tmp_a.magic = tmp_b.magic = tmp_curve_order.magic = tmp_gx.magic = WORD(0);
        tmp_gy.magic = tmp_gz.magic = tmp_order.magic = tmp_cofactor.magic = WORD(0);
        tmp_order_bitlen.magic = tmp_p_bitlen.magic = WORD(0);

        MUST_HAVE(((out_params != NULL) && (in_str_params != NULL)), ret, err);

        ret = local_memset(out_params, 0, sizeof(ec_params)); EG(ret, err);

        /*
         * We first need to import p, the prime defining Fp and associated
         * Montgomery parameters (r, r^2 and mpinv)
         */
        ret = nn_init_from_buf(&tmp_p, PARAM_BUF_PTR(in_str_params->p),
                        PARAM_BUF_LEN(in_str_params->p)); EG(ret, err);

        ret = nn_init_from_buf(&tmp_p_bitlen,
                        PARAM_BUF_PTR(in_str_params->p_bitlen),
                        PARAM_BUF_LEN(in_str_params->p_bitlen)); EG(ret, err);

        ret = nn_init_from_buf(&tmp_r, PARAM_BUF_PTR(in_str_params->r),
                        PARAM_BUF_LEN(in_str_params->r)); EG(ret, err);

        ret = nn_init_from_buf(&tmp_r_square,
                        PARAM_BUF_PTR(in_str_params->r_square),
                        PARAM_BUF_LEN(in_str_params->r_square)); EG(ret, err);

        ret = nn_init_from_buf(&tmp_mpinv,
                        PARAM_BUF_PTR(in_str_params->mpinv),
                        PARAM_BUF_LEN(in_str_params->mpinv)); EG(ret, err);

        ret = nn_init_from_buf(&tmp_p_shift,
                        PARAM_BUF_PTR(in_str_params->p_shift),
                        PARAM_BUF_LEN(in_str_params->p_shift)); EG(ret, err);

        ret = nn_init_from_buf(&tmp_p_normalized,
                        PARAM_BUF_PTR(in_str_params->p_normalized),
                        PARAM_BUF_LEN(in_str_params->p_normalized)); EG(ret, err);

        ret = nn_init_from_buf(&tmp_p_reciprocal,
                         PARAM_BUF_PTR(in_str_params->p_reciprocal),
                         PARAM_BUF_LEN(in_str_params->p_reciprocal)); EG(ret, err);

        /* From p, we can create global Fp context */
        ret = fp_ctx_init(&(out_params->ec_fp), &tmp_p,
                    (bitcnt_t)(tmp_p_bitlen.val[0]),
                    &tmp_r, &tmp_r_square,
                    tmp_mpinv.val[0], (bitcnt_t)tmp_p_shift.val[0],
                    &tmp_p_normalized, tmp_p_reciprocal.val[0]); EG(ret, err);

        /*
         * Having Fp context, we can import a and b, the coefficient of
         * of Weierstrass equation.
         */
        ret = fp_init_from_buf(&tmp_a, &(out_params->ec_fp),
                         PARAM_BUF_PTR(in_str_params->a),
                         PARAM_BUF_LEN(in_str_params->a)); EG(ret, err);
        ret = fp_init_from_buf(&tmp_b, &(out_params->ec_fp),
                         PARAM_BUF_PTR(in_str_params->b),
                         PARAM_BUF_LEN(in_str_params->b)); EG(ret, err);

        /*
         * Now we can store the number of points in the group generated
         * by g and the associated cofactor (i.e. npoints / order).
         */
        ret = nn_init_from_buf(&tmp_order,
                         PARAM_BUF_PTR(in_str_params->gen_order),
                         PARAM_BUF_LEN(in_str_params->gen_order)); EG(ret, err);
        ret = nn_init(&(out_params->ec_gen_order), (u16)(tmp_order.wlen * WORD_BYTES)); EG(ret, err);
        ret = nn_copy(&(out_params->ec_gen_order), &tmp_order); EG(ret, err);

        ret = nn_init_from_buf(&tmp_order_bitlen,
                         PARAM_BUF_PTR(in_str_params->gen_order_bitlen),
                         PARAM_BUF_LEN(in_str_params->gen_order_bitlen)); EG(ret, err);
        out_params->ec_gen_order_bitlen = (bitcnt_t)(tmp_order_bitlen.val[0]);

        ret = nn_init_from_buf(&tmp_cofactor,
                         PARAM_BUF_PTR(in_str_params->cofactor),
                         PARAM_BUF_LEN(in_str_params->cofactor)); EG(ret, err);
        ret = nn_init(&(out_params->ec_gen_cofactor),
                (u16)(tmp_cofactor.wlen * WORD_BYTES)); EG(ret, err);
        ret = nn_copy(&(out_params->ec_gen_cofactor), &tmp_cofactor); EG(ret, err);

        /* Now we can store the number of points on the curve (curve order) */
        ret = nn_init_from_buf(&tmp_curve_order,
                         PARAM_BUF_PTR(in_str_params->curve_order),
                         PARAM_BUF_LEN(in_str_params->curve_order)); EG(ret, err);

        /* Now, we can create curve context from a and b. */
        ret = ec_shortw_crv_init(&(out_params->ec_curve), &tmp_a, &tmp_b, &tmp_curve_order); EG(ret, err);

        /* Let's now import G from its affine coordinates (gx,gy) */
        ret = fp_init_from_buf(&tmp_gx, &(out_params->ec_fp),
                         PARAM_BUF_PTR(in_str_params->gx),
                         PARAM_BUF_LEN(in_str_params->gx)); EG(ret, err);
        ret = fp_init_from_buf(&tmp_gy, &(out_params->ec_fp),
                         PARAM_BUF_PTR(in_str_params->gy),
                         PARAM_BUF_LEN(in_str_params->gy)); EG(ret, err);
        ret = fp_init_from_buf(&tmp_gz, &(out_params->ec_fp),
                         PARAM_BUF_PTR(in_str_params->gz),
                         PARAM_BUF_LEN(in_str_params->gz)); EG(ret, err);
        ret = prj_pt_init_from_coords(&(out_params->ec_gen),
                                &(out_params->ec_curve),
                                &tmp_gx, &tmp_gy, &tmp_gz); EG(ret, err);

#if !defined(USE_SMALL_STACK)
        /* Let's get the optional alpha transfert coefficients */
        ret = fp_init_from_buf(&(out_params->ec_alpha_montgomery), &(out_params->ec_fp),
                         PARAM_BUF_PTR(in_str_params->alpha_montgomery),
                         PARAM_BUF_LEN(in_str_params->alpha_montgomery)); EG(ret, err);
        ret = fp_init_from_buf(&(out_params->ec_gamma_montgomery), &(out_params->ec_fp),
                         PARAM_BUF_PTR(in_str_params->gamma_montgomery),
                         PARAM_BUF_LEN(in_str_params->gamma_montgomery)); EG(ret, err);

        ret = fp_init_from_buf(&(out_params->ec_alpha_edwards), &(out_params->ec_fp),
                         PARAM_BUF_PTR(in_str_params->alpha_edwards),
                         PARAM_BUF_LEN(in_str_params->alpha_edwards)); EG(ret, err);
#endif

        /* Import a local copy of curve OID */
        MUST_HAVE(in_str_params->oid->buflen < MAX_CURVE_OID_LEN, ret, err);
        ret = local_memset(out_params->curve_oid, 0, MAX_CURVE_OID_LEN); EG(ret, err);
        ret = local_strncpy((char *)(out_params->curve_oid),
                      (const char *)(in_str_params->oid->buf),
                      in_str_params->oid->buflen); EG(ret, err);

        /* Import a local copy of curve name */
        MUST_HAVE(in_str_params->name->buflen < MAX_CURVE_NAME_LEN, ret, err);
        ret = local_memset(out_params->curve_name, 0, MAX_CURVE_NAME_LEN); EG(ret, err);
        ret = local_strncpy((char *)(out_params->curve_name),
                      (const char *)(in_str_params->name->buf),
                      in_str_params->name->buflen); EG(ret, err);

        /* Get the curve type */
        ret = ec_get_curve_type_by_name(in_str_params->name->buf,
                                        in_str_params->name->buflen,
                                        &curve_type); EG(ret, err);
        MUST_HAVE(curve_type != UNKNOWN_CURVE, ret, err);
        out_params->curve_type = curve_type;

err:
        /* Uninit temporary parameters */
        nn_uninit(&tmp_p_bitlen);
        nn_uninit(&tmp_order_bitlen);
        nn_uninit(&tmp_p);
        nn_uninit(&tmp_r);
        nn_uninit(&tmp_r_square);
        nn_uninit(&tmp_mpinv);
        nn_uninit(&tmp_p_shift);
        nn_uninit(&tmp_p_normalized);
        nn_uninit(&tmp_p_reciprocal);
        fp_uninit(&tmp_a);
        fp_uninit(&tmp_b);
        nn_uninit(&tmp_curve_order);
        fp_uninit(&tmp_gx);
        fp_uninit(&tmp_gy);
        fp_uninit(&tmp_gz);
        nn_uninit(&tmp_order);
        nn_uninit(&tmp_cofactor);

        return ret;
}