crypto/dh/dh_group_params.c

   1 /*
   2  * Copyright 2017-2021 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 = ossl_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->dirty_cnt++;
  38     return dh;
  39 }
  40
  41 DH *ossl_dh_new_by_nid_ex(OSSL_LIB_CTX *libctx, int nid)
  42 {
  43     const DH_NAMED_GROUP *group;
  44
  45     if ((group = ossl_ffc_uid_to_dh_named_group(nid)) != NULL)
  46         return dh_param_init(libctx, group);
  47
  48     ERR_raise(ERR_LIB_DH, DH_R_INVALID_PARAMETER_NID);
  49     return NULL;
  50 }
  51
  52 DH *DH_new_by_nid(int nid)
  53 {
  54     return ossl_dh_new_by_nid_ex(NULL, nid);
  55 }
  56
  57 void ossl_dh_cache_named_group(DH *dh)
  58 {
  59     const DH_NAMED_GROUP *group;
  60
  61     if (dh == NULL)
  62         return;
  63
  64     dh->params.nid = NID_undef; /* flush cached value */
  65
  66     /* Exit if p or g is not set */
  67     if (dh->params.p == NULL
  68         || dh->params.g == NULL)
  69         return;
  70
  71     if ((group = ossl_ffc_numbers_to_dh_named_group(dh->params.p,
  72                                                     dh->params.q,
  73                                                     dh->params.g)) != NULL) {
  74         if (dh->params.q == NULL)
  75             dh->params.q = (BIGNUM *)ossl_ffc_named_group_get_q(group);
  76         /* cache the nid */
  77         dh->params.nid = ossl_ffc_named_group_get_uid(group);
  78         dh->dirty_cnt++;
  79     }
  80 }
  81
  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
  93 int DH_get_nid(const DH *dh)
  94 {
  95     if (dh == NULL)
  96         return NID_undef;
  97
  98     return dh->params.nid;
  99 }