/*

 * Copyright 2017-2022 The OpenSSL Project Authors. All Rights Reserved.

 *

 * Licensed under the Apache License 2.0 (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

 */

/* DH parameters from RFC7919 and RFC3526 */

/*

 * DH low level APIs are deprecated for public use, but still ok for

 * internal use.

 */

#include "internal/deprecated.h"

#include <stdio.h>

#include "internal/cryptlib.h"

#include "internal/ffc.h"

#include "dh_local.h"

#include <openssl/bn.h>

#include <openssl/objects.h>

#include "internal/nelem.h"

#include "crypto/dh.h"

static DH *dh_param_init(OSSL_LIB_CTX *libctx, const DH_NAMED_GROUP *group)

{

    DH *dh = ossl_dh_new_ex(libctx);

    if (dh == NULL)

        return NULL;

    ossl_ffc_named_group_set(&dh->params, group);

    dh->params.nid = ossl_ffc_named_group_get_uid(group);

    dh->dirty_cnt++;

    return dh;

}

DH *ossl_dh_new_by_nid_ex(OSSL_LIB_CTX *libctx, int nid)

{

    const DH_NAMED_GROUP *group;

    if ((group = ossl_ffc_uid_to_dh_named_group(nid)) != NULL)

        return dh_param_init(libctx, group);

    ERR_raise(ERR_LIB_DH, DH_R_INVALID_PARAMETER_NID);

    return NULL;

}

DH *DH_new_by_nid(int nid)

{

    return ossl_dh_new_by_nid_ex(NULL, nid);

}

void ossl_dh_cache_named_group(DH *dh)

{

    const DH_NAMED_GROUP *group;

    if (dh == NULL)

        return;

    dh->params.nid = NID_undef; /* flush cached value */

    /* Exit if p or g is not set */

    if (dh->params.p == NULL

        || dh->params.g == NULL)

        return;

    if ((group = ossl_ffc_numbers_to_dh_named_group(dh->params.p,

                                                    dh->params.q,

                                                    dh->params.g)) != NULL) {

        if (dh->params.q == NULL)

            dh->params.q = (BIGNUM *)ossl_ffc_named_group_get_q(group);

        /* cache the nid and default key length */

        dh->params.nid = ossl_ffc_named_group_get_uid(group);

        dh->params.keylength = ossl_ffc_named_group_get_keylength(group);

        dh->dirty_cnt++;

    }

}

int ossl_dh_is_named_safe_prime_group(const DH *dh)

{

    int id = DH_get_nid(dh);

    /*

     * Exclude RFC5114 groups (id = 1..3) since they do not have

     * q = (p - 1) / 2

     */

    return (id > 3);

}

int DH_get_nid(const DH *dh)

{

    if (dh == NULL)

        return NID_undef;

    return dh->params.nid;

}