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