2 * Copyright 2017-2020 The OpenSSL Project Authors. All Rights Reserved.
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
10 /* DH parameters from RFC7919 and RFC3526 */
13 * DH low level APIs are deprecated for public use, but still ok for
16 #include "internal/deprecated.h"
19 #include "internal/cryptlib.h"
21 #include <openssl/bn.h>
22 #include <openssl/objects.h>
23 #include "crypto/bn_dh.h"
24 #include "crypto/dh.h"
25 #include "crypto/security_bits.h"
28 #define FFDHE(sz) { NID_ffdhe##sz, sz, &_bignum_ffdhe##sz##_p }
29 #define MODP(sz) { NID_modp_##sz, sz, &_bignum_modp_##sz##_p }
31 typedef struct safe_prime_group_st {
37 static const SP_GROUP sp_groups[] = {
54 static DH *dh_new_by_nid_with_ctx(OPENSSL_CTX *libctx, int nid);
56 static DH *dh_param_init(OPENSSL_CTX *libctx, int nid, const BIGNUM *p,
60 DH *dh = dh_new_with_ctx(libctx);
66 /* Set q = (p - 1) / 2 (p is known to be odd so just shift right ) */
67 if (q == NULL || !BN_rshift1(q, q)) {
73 dh->params.p = (BIGNUM *)p;
74 dh->params.q = (BIGNUM *)q;
75 dh->params.g = (BIGNUM *)&_bignum_const_2;
76 /* Private key length = 2 * max_target_security_strength */
82 static DH *dh_new_by_nid_with_ctx(OPENSSL_CTX *libctx, int nid)
86 for (i = 0; i < (int)OSSL_NELEM(sp_groups); ++i) {
87 if (sp_groups[i].nid == nid) {
88 int max_target_security_strength =
89 ifc_ffc_compute_security_bits(sp_groups[i].nbits);
92 * The last parameter specified here is
93 * 2 * max_target_security_strength.
94 * See SP800-56Ar3 Table(s) 25 & 26.
96 return dh_param_init(libctx, nid, sp_groups[i].p,
97 2 * max_target_security_strength);
100 DHerr(0, DH_R_INVALID_PARAMETER_NID);
104 DH *DH_new_by_nid(int nid)
106 return dh_new_by_nid_with_ctx(NULL, nid);
110 int DH_get_nid(DH *dh)
118 nid = dh->params.nid;
119 /* Just return if it is already cached */
120 if (nid != NID_undef)
123 if (BN_get_word(dh->params.g) != 2)
126 for (i = 0; i < (int)OSSL_NELEM(sp_groups); ++i) {
127 /* If a matching p is found then we will break out of the loop */
128 if (!BN_cmp(dh->params.p, sp_groups[i].p)) {
129 /* Set q = (p - 1) / 2 (p is known to be odd so just shift right ) */
130 q = BN_dup(dh->params.p);
132 if (q == NULL || !BN_rshift1(q, q))
133 break; /* returns nid = NID_undef on failure */
135 /* Verify q is correct if it exists */
136 if (dh->params.q != NULL) {
137 if (BN_cmp(dh->params.q, q) != 0)
138 break; /* returns nid = NID_undef if q does not match */
140 /* assign the calculated q */
142 q = NULL; /* set to NULL so it is not freed */
144 dh->params.nid = sp_groups[i].nid; /* cache the nid */
145 dh->length = 2 * ifc_ffc_compute_security_bits(sp_groups[i].nbits);