xref: /openssl/crypto/dh/dh_group_params.c (revision ddb13b28)
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 
dh_param_init(OSSL_LIB_CTX * libctx,const DH_NAMED_GROUP * group)27 static 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 
ossl_dh_new_by_nid_ex(OSSL_LIB_CTX * libctx,int nid)40 DH *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 
DH_new_by_nid(int nid)51 DH *DH_new_by_nid(int nid)
52 {
53     return ossl_dh_new_by_nid_ex(NULL, nid);
54 }
55 
ossl_dh_cache_named_group(DH * dh)56 void 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 
ossl_dh_is_named_safe_prime_group(const DH * dh)82 int 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 
DH_get_nid(const DH * dh)93 int DH_get_nid(const DH *dh)
94 {
95     if (dh == NULL)
96         return NID_undef;
97 
98     return dh->params.nid;
99 }
100