1 /*
2 * Diffie-Hellman-Merkle key exchange (prime generation)
3 *
4 * Copyright The Mbed TLS Contributors
5 * SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
6 *
7 * This file is provided under the Apache License 2.0, or the
8 * GNU General Public License v2.0 or later.
9 *
10 * **********
11 * Apache License 2.0:
12 *
13 * Licensed under the Apache License, Version 2.0 (the "License"); you may
14 * not use this file except in compliance with the License.
15 * You may obtain a copy of the License at
16 *
17 * http://www.apache.org/licenses/LICENSE-2.0
18 *
19 * Unless required by applicable law or agreed to in writing, software
20 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
21 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
22 * See the License for the specific language governing permissions and
23 * limitations under the License.
24 *
25 * **********
26 *
27 * **********
28 * GNU General Public License v2.0 or later:
29 *
30 * This program is free software; you can redistribute it and/or modify
31 * it under the terms of the GNU General Public License as published by
32 * the Free Software Foundation; either version 2 of the License, or
33 * (at your option) any later version.
34 *
35 * This program is distributed in the hope that it will be useful,
36 * but WITHOUT ANY WARRANTY; without even the implied warranty of
37 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
38 * GNU General Public License for more details.
39 *
40 * You should have received a copy of the GNU General Public License along
41 * with this program; if not, write to the Free Software Foundation, Inc.,
42 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
43 *
44 * **********
45 */
46
47 #if !defined(MBEDTLS_CONFIG_FILE)
48 #include "mbedtls/config.h"
49 #else
50 #include MBEDTLS_CONFIG_FILE
51 #endif
52
53 #if defined(MBEDTLS_PLATFORM_C)
54 #include "mbedtls/platform.h"
55 #else
56 #include <stdio.h>
57 #include <stdlib.h>
58 #define mbedtls_printf printf
59 #define mbedtls_time_t time_t
60 #define mbedtls_exit exit
61 #define MBEDTLS_EXIT_SUCCESS EXIT_SUCCESS
62 #define MBEDTLS_EXIT_FAILURE EXIT_FAILURE
63 #endif /* MBEDTLS_PLATFORM_C */
64
65 #if !defined(MBEDTLS_BIGNUM_C) || !defined(MBEDTLS_ENTROPY_C) || \
66 !defined(MBEDTLS_FS_IO) || !defined(MBEDTLS_CTR_DRBG_C) || \
67 !defined(MBEDTLS_GENPRIME)
main(void)68 int main( void )
69 {
70 mbedtls_printf("MBEDTLS_BIGNUM_C and/or MBEDTLS_ENTROPY_C and/or "
71 "MBEDTLS_FS_IO and/or MBEDTLS_CTR_DRBG_C and/or "
72 "MBEDTLS_GENPRIME not defined.\n");
73 mbedtls_exit( 0 );
74 }
75 #else
76
77 #include "mbedtls/bignum.h"
78 #include "mbedtls/entropy.h"
79 #include "mbedtls/ctr_drbg.h"
80
81 #include <stdio.h>
82 #include <string.h>
83
84 #define USAGE \
85 "\n usage: dh_genprime param=<>...\n" \
86 "\n acceprable parameters:\n" \
87 " bits=%%d default: 2048\n"
88
89 #define DFL_BITS 2048
90
91 /*
92 * Note: G = 4 is always a quadratic residue mod P,
93 * so it is a generator of order Q (with P = 2*Q+1).
94 */
95 #define GENERATOR "4"
96
97
main(int argc,char ** argv)98 int main( int argc, char **argv )
99 {
100 int ret = 1;
101 int exit_code = MBEDTLS_EXIT_FAILURE;
102 mbedtls_mpi G, P, Q;
103 mbedtls_entropy_context entropy;
104 mbedtls_ctr_drbg_context ctr_drbg;
105 const char *pers = "dh_genprime";
106 FILE *fout;
107 int nbits = DFL_BITS;
108 int i;
109 char *p, *q;
110
111 mbedtls_mpi_init( &G ); mbedtls_mpi_init( &P ); mbedtls_mpi_init( &Q );
112 mbedtls_ctr_drbg_init( &ctr_drbg );
113 mbedtls_entropy_init( &entropy );
114
115 if( argc == 0 )
116 {
117 usage:
118 mbedtls_printf( USAGE );
119 goto exit;
120 }
121
122 for( i = 1; i < argc; i++ )
123 {
124 p = argv[i];
125 if( ( q = strchr( p, '=' ) ) == NULL )
126 goto usage;
127 *q++ = '\0';
128
129 if( strcmp( p, "bits" ) == 0 )
130 {
131 nbits = atoi( q );
132 if( nbits < 0 || nbits > MBEDTLS_MPI_MAX_BITS )
133 goto usage;
134 }
135 else
136 goto usage;
137 }
138
139 if( ( ret = mbedtls_mpi_read_string( &G, 10, GENERATOR ) ) != 0 )
140 {
141 mbedtls_printf( " failed\n ! mbedtls_mpi_read_string returned %d\n", ret );
142 goto exit;
143 }
144
145 mbedtls_printf( " ! Generating large primes may take minutes!\n" );
146
147 mbedtls_printf( "\n . Seeding the random number generator..." );
148 fflush( stdout );
149
150 if( ( ret = mbedtls_ctr_drbg_seed( &ctr_drbg, mbedtls_entropy_func, &entropy,
151 (const unsigned char *) pers,
152 strlen( pers ) ) ) != 0 )
153 {
154 mbedtls_printf( " failed\n ! mbedtls_ctr_drbg_seed returned %d\n", ret );
155 goto exit;
156 }
157
158 mbedtls_printf( " ok\n . Generating the modulus, please wait..." );
159 fflush( stdout );
160
161 /*
162 * This can take a long time...
163 */
164 if( ( ret = mbedtls_mpi_gen_prime( &P, nbits, 1,
165 mbedtls_ctr_drbg_random, &ctr_drbg ) ) != 0 )
166 {
167 mbedtls_printf( " failed\n ! mbedtls_mpi_gen_prime returned %d\n\n", ret );
168 goto exit;
169 }
170
171 mbedtls_printf( " ok\n . Verifying that Q = (P-1)/2 is prime..." );
172 fflush( stdout );
173
174 if( ( ret = mbedtls_mpi_sub_int( &Q, &P, 1 ) ) != 0 )
175 {
176 mbedtls_printf( " failed\n ! mbedtls_mpi_sub_int returned %d\n\n", ret );
177 goto exit;
178 }
179
180 if( ( ret = mbedtls_mpi_div_int( &Q, NULL, &Q, 2 ) ) != 0 )
181 {
182 mbedtls_printf( " failed\n ! mbedtls_mpi_div_int returned %d\n\n", ret );
183 goto exit;
184 }
185
186 if( ( ret = mbedtls_mpi_is_prime_ext( &Q, 50, mbedtls_ctr_drbg_random, &ctr_drbg ) ) != 0 )
187 {
188 mbedtls_printf( " failed\n ! mbedtls_mpi_is_prime returned %d\n\n", ret );
189 goto exit;
190 }
191
192 mbedtls_printf( " ok\n . Exporting the value in dh_prime.txt..." );
193 fflush( stdout );
194
195 if( ( fout = fopen( "dh_prime.txt", "wb+" ) ) == NULL )
196 {
197 mbedtls_printf( " failed\n ! Could not create dh_prime.txt\n\n" );
198 goto exit;
199 }
200
201 if( ( ret = mbedtls_mpi_write_file( "P = ", &P, 16, fout ) != 0 ) ||
202 ( ret = mbedtls_mpi_write_file( "G = ", &G, 16, fout ) != 0 ) )
203 {
204 mbedtls_printf( " failed\n ! mbedtls_mpi_write_file returned %d\n\n", ret );
205 fclose( fout );
206 goto exit;
207 }
208
209 mbedtls_printf( " ok\n\n" );
210 fclose( fout );
211
212 exit_code = MBEDTLS_EXIT_SUCCESS;
213
214 exit:
215
216 mbedtls_mpi_free( &G ); mbedtls_mpi_free( &P ); mbedtls_mpi_free( &Q );
217 mbedtls_ctr_drbg_free( &ctr_drbg );
218 mbedtls_entropy_free( &entropy );
219
220 #if defined(_WIN32)
221 mbedtls_printf( " Press Enter to exit this program.\n" );
222 fflush( stdout ); getchar();
223 #endif
224
225 mbedtls_exit( exit_code );
226 }
227 #endif /* MBEDTLS_BIGNUM_C && MBEDTLS_ENTROPY_C && MBEDTLS_FS_IO &&
228 MBEDTLS_CTR_DRBG_C && MBEDTLS_GENPRIME */
229