/*

 * Copyright 2017 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 <stdio.h>

#include "internal/cryptlib.h"

#include "dh_locl.h"

#include <openssl/bn.h>

#include <openssl/objects.h>

#include "internal/bn_dh.h"

static DH *dh_param_init(const BIGNUM *p, int32_t nbits)

{

    DH *dh = DH_new();

    if (dh == NULL)

        return NULL;

    dh->p = (BIGNUM *)p;

    dh->g = (BIGNUM *)&_bignum_const_2;

    dh->length = nbits;

    return dh;

}

DH *DH_new_by_nid(int nid)

{

    switch (nid) {

    case NID_ffdhe2048:

        return dh_param_init(&_bignum_ffdhe2048_p, 225);

    case NID_ffdhe3072:

        return dh_param_init(&_bignum_ffdhe3072_p, 275);

    case NID_ffdhe4096:

        return dh_param_init(&_bignum_ffdhe4096_p, 325);

    case NID_ffdhe6144:

        return dh_param_init(&_bignum_ffdhe6144_p, 375);

    case NID_ffdhe8192:

        return dh_param_init(&_bignum_ffdhe8192_p, 400);

    default:

        DHerr(DH_F_DH_NEW_BY_NID, DH_R_INVALID_PARAMETER_NID);

        return NULL;

    }

}

int DH_get_nid(const DH *dh)

{

    int nid;

    if (BN_get_word(dh->g) != 2)

        return NID_undef;

    if (!BN_cmp(dh->p, &_bignum_ffdhe2048_p))

        nid = NID_ffdhe2048;

    else if (!BN_cmp(dh->p, &_bignum_ffdhe3072_p))

        nid = NID_ffdhe3072;

    else if (!BN_cmp(dh->p, &_bignum_ffdhe4096_p))

        nid = NID_ffdhe4096;

    else if (!BN_cmp(dh->p, &_bignum_ffdhe6144_p))

        nid = NID_ffdhe6144;

    else if (!BN_cmp(dh->p, &_bignum_ffdhe8192_p))

        nid = NID_ffdhe8192;

    else

        return NID_undef;

    if (dh->q != NULL) {

        BIGNUM *q = BN_dup(dh->p);

        /* Check q = p * 2 + 1 we already know q is odd, so just shift right */

        if (q == NULL || !BN_rshift1(q, q) || !BN_cmp(dh->q, q))

            nid = NID_undef;

        BN_free(q);

    }

    return nid;

}