src/dh.c

   1 /*
   2  * Copyright (C) 2001-2012 Free Software Foundation, Inc.
   3  *
   4  * This file is part of GnuTLS.
   5  *
   6  * GnuTLS is free software: you can redistribute it and/or modify it
   7  * under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation, either version 3 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * GnuTLS is distributed in the hope that it will be useful, but
  12  * WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  * General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program.  If not, see
  18  * <http://www.gnu.org/licenses/>.
  19  */
  20
  21 #include <config.h>
  22
  23 #include <stdio.h>
  24 #include <string.h>
  25 #include <stdlib.h>
  26 #include <unistd.h>
  27 #include <gnutls/gnutls.h>
  28 #include <read-file.h>
  29 #include <certtool-common.h>
  30
  31 /* Generates Diffie-Hellman parameters (a prime and a generator
  32  * of the group). Exports them in PKCS #3 format. Used by certtool.
  33  */
  34
  35 extern FILE *outfile;
  36 extern FILE *infile;
  37
  38 static void
  39 print_dh_info (gnutls_datum_t * p, gnutls_datum_t * g, unsigned int q_bits)
  40 {
  41 unsigned int i;
  42
  43   fprintf (outfile, "\nGenerator (%d bits): ", g->size*8);
  44
  45   for (i = 0; i < g->size; i++)
  46     {
  47       if (i != 0 && i % 12 == 0)
  48         fprintf (outfile, "\n\t");
  49       else if (i != 0 && i != g->size)
  50         fprintf (outfile, ":");
  51
  52       fprintf (outfile, "%.2x", g->data[i]);
  53     }
  54
  55   fprintf (outfile, "\n\n");
  56
  57   /* print prime */
  58
  59   fprintf (outfile, "Prime (%d bits):", p->size*8);
  60
  61   for (i = 0; i < p->size; i++)
  62     {
  63       if (i % 12 == 0)
  64         fprintf (outfile, "\n\t");
  65       else if (i != 0 && i != p->size)
  66         fprintf (outfile, ":");
  67       fprintf (outfile, "%.2x", p->data[i]);
  68     }
  69
  70   if (q_bits > 0)
  71     fprintf (outfile, "\n\nRecommended key length: %d bits\n", q_bits);
  72   fprintf (outfile, "\n");
  73
  74 }
  75
  76 void dh_info (common_info_st * ci)
  77 {
  78   gnutls_datum_t params;
  79   size_t size;
  80   int ret;
  81   gnutls_dh_params_t dh_params;
  82   gnutls_datum_t p, g;
  83   unsigned int q_bits = 0;
  84
  85   if (gnutls_dh_params_init (&dh_params) < 0)
  86     {
  87       fprintf (stderr, "Error in dh parameter initialization\n");
  88       exit (1);
  89     }
  90
  91   params.data = (void*)fread_file (infile, &size);
  92   params.size = size;
  93
  94   ret =
  95     gnutls_dh_params_import_pkcs3 (dh_params, &params, GNUTLS_X509_FMT_PEM);
  96   if (ret < 0)
  97     {
  98       fprintf (stderr, "Error parsing dh params: %s\n", gnutls_strerror (ret));
  99       exit (1);
 100     }
 101
 102   ret = gnutls_dh_params_export_raw (dh_params, &p, &g, &q_bits);
 103   if (ret < 0)
 104     {
 105       fprintf (stderr, "Error exporting parameters: %s\n",
 106                gnutls_strerror (ret));
 107       exit (1);
 108     }
 109
 110   print_dh_info (&p, &g, q_bits);
 111
 112   {                             /* generate a PKCS#3 structure */
 113     size_t len = buffer_size;
 114
 115     ret = gnutls_dh_params_export_pkcs3 (dh_params, GNUTLS_X509_FMT_PEM,
 116                                          buffer, &len);
 117
 118     if (ret == 0)
 119       {
 120         fprintf (outfile, "\n%s", buffer);
 121       }
 122     else
 123       {
 124         fprintf (stderr, "Error: %s\n", gnutls_strerror (ret));
 125       }
 126
 127   }
 128
 129   gnutls_dh_params_deinit(dh_params);
 130 }
 131
 132 /* If how is zero then the included parameters are used.
 133  */
 134 int
 135 generate_prime (int how, common_info_st * info)
 136 {
 137   int ret;
 138   gnutls_dh_params_t dh_params;
 139   gnutls_datum_t p, g;
 140   int bits = get_bits (GNUTLS_PK_DH, info->bits, info->sec_param, 1);
 141   unsigned int q_bits = 0;
 142
 143   gnutls_dh_params_init (&dh_params);
 144
 145   if (how != 0)
 146     {
 147       fprintf (stderr, "Generating DH parameters (%d bits)...\n", bits);
 148       fprintf (stderr, "(might take long time)\n");
 149     }
 150   else
 151     fprintf (stderr, "Retrieving DH parameters...\n");
 152
 153   if (how != 0)
 154     {
 155       ret = gnutls_dh_params_generate2 (dh_params, bits);
 156       if (ret < 0)
 157         {
 158           fprintf (stderr, "Error generating parameters: %s\n",
 159                    gnutls_strerror (ret));
 160           exit (1);
 161         }
 162
 163       ret = gnutls_dh_params_export_raw (dh_params, &p, &g, &q_bits);
 164       if (ret < 0)
 165         {
 166           fprintf (stderr, "Error exporting parameters: %s\n",
 167                    gnutls_strerror (ret));
 168           exit (1);
 169         }
 170     }
 171   else
 172     {
 173 #ifdef ENABLE_SRP
 174       if (bits <= 1024)
 175         {
 176           p = gnutls_srp_1024_group_prime;
 177           g = gnutls_srp_1024_group_generator;
 178           bits = 1024;
 179         }
 180       else if (bits <= 1536)
 181         {
 182           p = gnutls_srp_1536_group_prime;
 183           g = gnutls_srp_1536_group_generator;
 184           bits = 1536;
 185         }
 186       else if (bits <= 2048)
 187         {
 188           p = gnutls_srp_2048_group_prime;
 189           g = gnutls_srp_2048_group_generator;
 190           bits = 2048;
 191         }
 192       else if (bits <= 3072)
 193         {
 194           p = gnutls_srp_3072_group_prime;
 195           g = gnutls_srp_3072_group_generator;
 196           bits = 3072;
 197         }
 198       else
 199         {
 200           p = gnutls_srp_4096_group_prime;
 201           g = gnutls_srp_4096_group_generator;
 202           bits = 4096;
 203         }
 204
 205       ret = gnutls_dh_params_import_raw (dh_params, &p, &g);
 206       if (ret < 0)
 207         {
 208           fprintf (stderr, "Error exporting parameters: %s\n",
 209                    gnutls_strerror (ret));
 210           exit (1);
 211         }
 212 #else
 213       fprintf (stderr, "Parameters unavailable as SRP is disabled.\n");
 214       exit (1);
 215 #endif
 216     }
 217
 218   print_dh_info (&p, &g, q_bits);
 219
 220   {                             /* generate a PKCS#3 structure */
 221     size_t len = buffer_size;
 222
 223     ret = gnutls_dh_params_export_pkcs3 (dh_params, GNUTLS_X509_FMT_PEM,
 224                                          buffer, &len);
 225
 226     if (ret == 0)
 227       {
 228         fprintf (outfile, "\n%s", buffer);
 229       }
 230     else
 231       {
 232         fprintf (stderr, "Error: %s\n", gnutls_strerror (ret));
 233       }
 234
 235   }
 236
 237   gnutls_dh_params_deinit(dh_params);
 238
 239   return 0;
 240 }
 241