/*

 * Copyright 2002-2016 The OpenSSL Project Authors. All Rights Reserved.

 *

 * Licensed under the OpenSSL license (the "License").  You may not use

 * this file except in compliance with the License.  You can obtain a copy

 * in the file LICENSE in the source distribution or at

 * https://www.openssl.org/source/license.html

 */

#include "ec_lcl.h"

#include <openssl/err.h>

int EC_GROUP_check(const EC_GROUP *group, BN_CTX *ctx)

{

    int ret = 0;

    const BIGNUM *order;

    BN_CTX *new_ctx = NULL;

    EC_POINT *point = NULL;

    /* Custom curves assumed to be correct */

    if ((group->meth->flags & EC_FLAGS_CUSTOM_CURVE) != 0)

        return 1;

    if (ctx == NULL) {

        ctx = new_ctx = BN_CTX_new();

        if (ctx == NULL) {

            ECerr(EC_F_EC_GROUP_CHECK, ERR_R_MALLOC_FAILURE);

            goto err;

        }

    }

    /* check the discriminant */

    if (!EC_GROUP_check_discriminant(group, ctx)) {

        ECerr(EC_F_EC_GROUP_CHECK, EC_R_DISCRIMINANT_IS_ZERO);

        goto err;

    }

    /* check the generator */

    if (group->generator == NULL) {

        ECerr(EC_F_EC_GROUP_CHECK, EC_R_UNDEFINED_GENERATOR);

        goto err;

    }

    if (EC_POINT_is_on_curve(group, group->generator, ctx) <= 0) {

        ECerr(EC_F_EC_GROUP_CHECK, EC_R_POINT_IS_NOT_ON_CURVE);

        goto err;

    }

    /* check the order of the generator */

    if ((point = EC_POINT_new(group)) == NULL)

        goto err;

    order = EC_GROUP_get0_order(group);

    if (order == NULL)

        goto err;

    if (BN_is_zero(order)) {

        ECerr(EC_F_EC_GROUP_CHECK, EC_R_UNDEFINED_ORDER);

        goto err;

    }

    if (!EC_POINT_mul(group, point, order, NULL, NULL, ctx))

        goto err;

    if (!EC_POINT_is_at_infinity(group, point)) {

        ECerr(EC_F_EC_GROUP_CHECK, EC_R_INVALID_GROUP_ORDER);

        goto err;

    }

    ret = 1;

 err:

    BN_CTX_free(new_ctx);

    EC_POINT_free(point);

    return ret;

}