crypto/dh/dh_group_params.c

   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
  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_pqg(&dh->params, group);
  35     dh->params.nid = ossl_ffc_named_group_get_uid(group);
  36     dh->dirty_cnt++;
  37     return dh;
  38 }
  39
  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
  51 DH *DH_new_by_nid(int nid)
  52 {
  53     return ossl_dh_new_by_nid_ex(NULL, nid);
  54 }
  55
  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 */
  76         dh->params.nid = ossl_ffc_named_group_get_uid(group);
  77         dh->dirty_cnt++;
  78     }
  79 }
  80
  81 int ossl_dh_is_named_safe_prime_group(const DH *dh)
  82 {
  83     int id = DH_get_nid(dh);
  84
  85     /*
  86      * Exclude RFC5114 groups (id = 1..3) since they do not have
  87      * q = (p - 1) / 2
  88      */
  89     return (id > 3);
  90 }
  91
  92 int DH_get_nid(const DH *dh)
  93 {
  94     if (dh == NULL)
  95         return NID_undef;
  96
  97     return dh->params.nid;
  98 }