1/*
2 * Copyright 2017-2022 The OpenSSL Project Authors. All Rights Reserved.
3 *
4 * Licensed under the Apache License 2.0 (the "License").  You may not use
5 * this file except in compliance with the License.  You can obtain a copy
6 * in the file LICENSE in the source distribution or at
7 * https://www.openssl.org/source/license.html
8 */
9
10/* DH parameters from RFC7919 and RFC3526 */
11
12/*
13 * DH low level APIs are deprecated for public use, but still ok for
14 * internal use.
15 */
16#include "internal/deprecated.h"
17
18#include <stdio.h>
19#include "internal/cryptlib.h"
20#include "internal/ffc.h"
21#include "dh_local.h"
22#include <openssl/bn.h>
23#include <openssl/objects.h>
24#include "internal/nelem.h"
25#include "crypto/dh.h"
26
27static DH *dh_param_init(OSSL_LIB_CTX *libctx, const DH_NAMED_GROUP *group)
28{
29    DH *dh = ossl_dh_new_ex(libctx);
30
31    if (dh == NULL)
32        return NULL;
33
34    ossl_ffc_named_group_set(&dh->params, group);
35    dh->params.nid = ossl_ffc_named_group_get_uid(group);
36    dh->dirty_cnt++;
37    return dh;
38}
39
40DH *ossl_dh_new_by_nid_ex(OSSL_LIB_CTX *libctx, int nid)
41{
42    const DH_NAMED_GROUP *group;
43
44    if ((group = ossl_ffc_uid_to_dh_named_group(nid)) != NULL)
45        return dh_param_init(libctx, group);
46
47    ERR_raise(ERR_LIB_DH, DH_R_INVALID_PARAMETER_NID);
48    return NULL;
49}
50
51DH *DH_new_by_nid(int nid)
52{
53    return ossl_dh_new_by_nid_ex(NULL, nid);
54}
55
56void ossl_dh_cache_named_group(DH *dh)
57{
58    const DH_NAMED_GROUP *group;
59
60    if (dh == NULL)
61        return;
62
63    dh->params.nid = NID_undef; /* flush cached value */
64
65    /* Exit if p or g is not set */
66    if (dh->params.p == NULL
67        || dh->params.g == NULL)
68        return;
69
70    if ((group = ossl_ffc_numbers_to_dh_named_group(dh->params.p,
71                                                    dh->params.q,
72                                                    dh->params.g)) != NULL) {
73        if (dh->params.q == NULL)
74            dh->params.q = (BIGNUM *)ossl_ffc_named_group_get_q(group);
75        /* cache the nid and default key length */
76        dh->params.nid = ossl_ffc_named_group_get_uid(group);
77        dh->params.keylength = ossl_ffc_named_group_get_keylength(group);
78        dh->dirty_cnt++;
79    }
80}
81
82int ossl_dh_is_named_safe_prime_group(const DH *dh)
83{
84    int id = DH_get_nid(dh);
85
86    /*
87     * Exclude RFC5114 groups (id = 1..3) since they do not have
88     * q = (p - 1) / 2
89     */
90    return (id > 3);
91}
92
93int DH_get_nid(const DH *dh)
94{
95    if (dh == NULL)
96        return NID_undef;
97
98    return dh->params.nid;
99}
100