crypto/dh/dh_group_params.c

   1 /*
   2  * Copyright 2017-2020 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 #include "e_os.h" /* strcasecmp */
  27
  28 static DH *dh_param_init(OSSL_LIB_CTX *libctx, const DH_NAMED_GROUP *group)
  29 {
  30     DH *dh = dh_new_ex(libctx);
  31
  32     if (dh == NULL)
  33         return NULL;
  34
  35     ossl_ffc_named_group_set_pqg(&dh->params, group);
  36     dh->params.nid = ossl_ffc_named_group_get_uid(group);
  37     dh->length = BN_num_bits(dh->params.q);
  38     dh->dirty_cnt++;
  39     return dh;
  40 }
  41
  42 DH *dh_new_by_nid_ex(OSSL_LIB_CTX *libctx, int nid)
  43 {
  44     const DH_NAMED_GROUP *group;
  45
  46     if ((group = ossl_ffc_uid_to_dh_named_group(nid)) != NULL)
  47         return dh_param_init(libctx, group);
  48
  49     ERR_raise(ERR_LIB_DH, DH_R_INVALID_PARAMETER_NID);
  50     return NULL;
  51 }
  52
  53 DH *DH_new_by_nid(int nid)
  54 {
  55     return dh_new_by_nid_ex(NULL, nid);
  56 }
  57
  58 void dh_cache_named_group(DH *dh)
  59 {
  60     const DH_NAMED_GROUP *group;
  61
  62     if (dh == NULL)
  63         return;
  64
  65     dh->params.nid = NID_undef; /* flush cached value */
  66
  67     /* Exit if p or g is not set */
  68     if (dh->params.p == NULL
  69         || dh->params.g == NULL)
  70         return;
  71
  72     if ((group = ossl_ffc_numbers_to_dh_named_group(dh->params.p,
  73                                                     dh->params.q,
  74                                                     dh->params.g)) != NULL) {
  75         if (dh->params.q == NULL)
  76             dh->params.q = (BIGNUM *)ossl_ffc_named_group_get_q(group);
  77         /* cache the nid */
  78         dh->params.nid = ossl_ffc_named_group_get_uid(group);
  79         dh->length = BN_num_bits(dh->params.q);
  80         dh->dirty_cnt++;
  81     }
  82 }
  83
  84 int ossl_dh_is_named_safe_prime_group(const DH *dh)
  85 {
  86     int id = DH_get_nid(dh);
  87
  88     /*
  89      * Exclude RFC5114 groups (id = 1..3) since they do not have
  90      * q = (p - 1) / 2
  91      */
  92     return (id > 3);
  93 }
  94
  95 int DH_get_nid(const DH *dh)
  96 {
  97     if (dh == NULL)
  98         return NID_undef;
  99
 100     return dh->params.nid;
 101 }