1 /*
2 * Diffie-Hellman-Merkle key exchange (prime generation)
3 *
4 * Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
5 * SPDX-License-Identifier: GPL-2.0
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License as published by
9 * the Free Software Foundation; either version 2 of the License, or
10 * (at your option) any later version.
11 *
12 * This program is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 * GNU General Public License for more details.
16 *
17 * You should have received a copy of the GNU General Public License along
18 * with this program; if not, write to the Free Software Foundation, Inc.,
19 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * This file is part of mbed TLS (https://tls.mbed.org)
22 */
23
24 #if !defined(MBEDTLS_CONFIG_FILE)
25 #include "mbedtls/config.h"
26 #else
27 #include MBEDTLS_CONFIG_FILE
28 #endif
29
30 #if defined(MBEDTLS_PLATFORM_C)
31 #include "mbedtls/platform.h"
32 #else
33 #include <stdio.h>
34 #include <stdlib.h>
35 #define mbedtls_printf printf
36 #define mbedtls_time_t time_t
37 #define MBEDTLS_EXIT_SUCCESS EXIT_SUCCESS
38 #define MBEDTLS_EXIT_FAILURE EXIT_FAILURE
39 #endif /* MBEDTLS_PLATFORM_C */
40
41 #if !defined(MBEDTLS_BIGNUM_C) || !defined(MBEDTLS_ENTROPY_C) || \
42 !defined(MBEDTLS_FS_IO) || !defined(MBEDTLS_CTR_DRBG_C) || \
43 !defined(MBEDTLS_GENPRIME)
main(void)44 int main( void )
45 {
46 mbedtls_printf("MBEDTLS_BIGNUM_C and/or MBEDTLS_ENTROPY_C and/or "
47 "MBEDTLS_FS_IO and/or MBEDTLS_CTR_DRBG_C and/or "
48 "MBEDTLS_GENPRIME not defined.\n");
49 return( 0 );
50 }
51 #else
52
53 #include "mbedtls/bignum.h"
54 #include "mbedtls/entropy.h"
55 #include "mbedtls/ctr_drbg.h"
56
57 #include <stdio.h>
58 #include <string.h>
59
60 #define USAGE \
61 "\n usage: dh_genprime param=<>...\n" \
62 "\n acceprable parameters:\n" \
63 " bits=%%d default: 2048\n"
64
65 #define DFL_BITS 2048
66
67 /*
68 * Note: G = 4 is always a quadratic residue mod P,
69 * so it is a generator of order Q (with P = 2*Q+1).
70 */
71 #define GENERATOR "4"
72
main(int argc,char ** argv)73 int main( int argc, char **argv )
74 {
75 int ret = 1;
76 int exit_code = MBEDTLS_EXIT_FAILURE;
77 mbedtls_mpi G, P, Q;
78 mbedtls_entropy_context entropy;
79 mbedtls_ctr_drbg_context ctr_drbg;
80 const char *pers = "dh_genprime";
81 FILE *fout;
82 int nbits = DFL_BITS;
83 int i;
84 char *p, *q;
85
86 mbedtls_mpi_init( &G ); mbedtls_mpi_init( &P ); mbedtls_mpi_init( &Q );
87 mbedtls_ctr_drbg_init( &ctr_drbg );
88 mbedtls_entropy_init( &entropy );
89
90 if( argc == 0 )
91 {
92 usage:
93 mbedtls_printf( USAGE );
94 return( exit_code );
95 }
96
97 for( i = 1; i < argc; i++ )
98 {
99 p = argv[i];
100 if( ( q = strchr( p, '=' ) ) == NULL )
101 goto usage;
102 *q++ = '\0';
103
104 if( strcmp( p, "bits" ) == 0 )
105 {
106 nbits = atoi( q );
107 if( nbits < 0 || nbits > MBEDTLS_MPI_MAX_BITS )
108 goto usage;
109 }
110 else
111 goto usage;
112 }
113
114 if( ( ret = mbedtls_mpi_read_string( &G, 10, GENERATOR ) ) != 0 )
115 {
116 mbedtls_printf( " failed\n ! mbedtls_mpi_read_string returned %d\n", ret );
117 goto exit;
118 }
119
120 mbedtls_printf( " ! Generating large primes may take minutes!\n" );
121
122 mbedtls_printf( "\n . Seeding the random number generator..." );
123 fflush( stdout );
124
125 if( ( ret = mbedtls_ctr_drbg_seed( &ctr_drbg, mbedtls_entropy_func, &entropy,
126 (const unsigned char *) pers,
127 strlen( pers ) ) ) != 0 )
128 {
129 mbedtls_printf( " failed\n ! mbedtls_ctr_drbg_seed returned %d\n", ret );
130 goto exit;
131 }
132
133 mbedtls_printf( " ok\n . Generating the modulus, please wait..." );
134 fflush( stdout );
135
136 /*
137 * This can take a long time...
138 */
139 if( ( ret = mbedtls_mpi_gen_prime( &P, nbits, 1,
140 mbedtls_ctr_drbg_random, &ctr_drbg ) ) != 0 )
141 {
142 mbedtls_printf( " failed\n ! mbedtls_mpi_gen_prime returned %d\n\n", ret );
143 goto exit;
144 }
145
146 mbedtls_printf( " ok\n . Verifying that Q = (P-1)/2 is prime..." );
147 fflush( stdout );
148
149 if( ( ret = mbedtls_mpi_sub_int( &Q, &P, 1 ) ) != 0 )
150 {
151 mbedtls_printf( " failed\n ! mbedtls_mpi_sub_int returned %d\n\n", ret );
152 goto exit;
153 }
154
155 if( ( ret = mbedtls_mpi_div_int( &Q, NULL, &Q, 2 ) ) != 0 )
156 {
157 mbedtls_printf( " failed\n ! mbedtls_mpi_div_int returned %d\n\n", ret );
158 goto exit;
159 }
160
161 if( ( ret = mbedtls_mpi_is_prime( &Q, mbedtls_ctr_drbg_random, &ctr_drbg ) ) != 0 )
162 {
163 mbedtls_printf( " failed\n ! mbedtls_mpi_is_prime returned %d\n\n", ret );
164 goto exit;
165 }
166
167 mbedtls_printf( " ok\n . Exporting the value in dh_prime.txt..." );
168 fflush( stdout );
169
170 if( ( fout = fopen( "dh_prime.txt", "wb+" ) ) == NULL )
171 {
172 mbedtls_printf( " failed\n ! Could not create dh_prime.txt\n\n" );
173 goto exit;
174 }
175
176 if( ( ret = mbedtls_mpi_write_file( "P = ", &P, 16, fout ) != 0 ) ||
177 ( ret = mbedtls_mpi_write_file( "G = ", &G, 16, fout ) != 0 ) )
178 {
179 mbedtls_printf( " failed\n ! mbedtls_mpi_write_file returned %d\n\n", ret );
180 fclose( fout );
181 goto exit;
182 }
183
184 mbedtls_printf( " ok\n\n" );
185 fclose( fout );
186
187 exit_code = MBEDTLS_EXIT_SUCCESS;
188
189 exit:
190
191 mbedtls_mpi_free( &G ); mbedtls_mpi_free( &P ); mbedtls_mpi_free( &Q );
192 mbedtls_ctr_drbg_free( &ctr_drbg );
193 mbedtls_entropy_free( &entropy );
194
195 #if defined(_WIN32)
196 mbedtls_printf( " Press Enter to exit this program.\n" );
197 fflush( stdout ); getchar();
198 #endif
199
200 return( exit_code );
201 }
202 #endif /* MBEDTLS_BIGNUM_C && MBEDTLS_ENTROPY_C && MBEDTLS_FS_IO &&
203 MBEDTLS_CTR_DRBG_C && MBEDTLS_GENPRIME */
204