1 /*
2 * RSA simple decryption program
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_exit exit
60 #define MBEDTLS_EXIT_SUCCESS EXIT_SUCCESS
61 #define MBEDTLS_EXIT_FAILURE EXIT_FAILURE
62 #endif /* MBEDTLS_PLATFORM_C */
63
64 #if defined(MBEDTLS_BIGNUM_C) && defined(MBEDTLS_RSA_C) && \
65 defined(MBEDTLS_FS_IO) && defined(MBEDTLS_ENTROPY_C) && \
66 defined(MBEDTLS_CTR_DRBG_C)
67 #include "mbedtls/rsa.h"
68 #include "mbedtls/entropy.h"
69 #include "mbedtls/ctr_drbg.h"
70
71 #include <string.h>
72
73 #endif
74
75 #if !defined(MBEDTLS_BIGNUM_C) || !defined(MBEDTLS_RSA_C) || \
76 !defined(MBEDTLS_FS_IO) || !defined(MBEDTLS_ENTROPY_C) || \
77 !defined(MBEDTLS_CTR_DRBG_C)
main(void)78 int main( void )
79 {
80 mbedtls_printf("MBEDTLS_BIGNUM_C and/or MBEDTLS_RSA_C and/or "
81 "MBEDTLS_FS_IO and/or MBEDTLS_ENTROPY_C and/or "
82 "MBEDTLS_CTR_DRBG_C not defined.\n");
83 mbedtls_exit( 0 );
84 }
85 #else
86
87
main(int argc,char * argv[])88 int main( int argc, char *argv[] )
89 {
90 FILE *f;
91 int ret = 1;
92 int exit_code = MBEDTLS_EXIT_FAILURE;
93 unsigned c;
94 size_t i;
95 mbedtls_rsa_context rsa;
96 mbedtls_mpi N, P, Q, D, E, DP, DQ, QP;
97 mbedtls_entropy_context entropy;
98 mbedtls_ctr_drbg_context ctr_drbg;
99 unsigned char result[1024];
100 unsigned char buf[512];
101 const char *pers = "rsa_decrypt";
102 ((void) argv);
103
104 memset(result, 0, sizeof( result ) );
105
106 if( argc != 1 )
107 {
108 mbedtls_printf( "usage: rsa_decrypt\n" );
109
110 #if defined(_WIN32)
111 mbedtls_printf( "\n" );
112 #endif
113
114 mbedtls_exit( exit_code );
115 }
116
117 mbedtls_printf( "\n . Seeding the random number generator..." );
118 fflush( stdout );
119
120 mbedtls_rsa_init( &rsa, MBEDTLS_RSA_PKCS_V15, 0 );
121 mbedtls_ctr_drbg_init( &ctr_drbg );
122 mbedtls_entropy_init( &entropy );
123 mbedtls_mpi_init( &N ); mbedtls_mpi_init( &P ); mbedtls_mpi_init( &Q );
124 mbedtls_mpi_init( &D ); mbedtls_mpi_init( &E ); mbedtls_mpi_init( &DP );
125 mbedtls_mpi_init( &DQ ); mbedtls_mpi_init( &QP );
126
127 ret = mbedtls_ctr_drbg_seed( &ctr_drbg, mbedtls_entropy_func,
128 &entropy, (const unsigned char *) pers,
129 strlen( pers ) );
130 if( ret != 0 )
131 {
132 mbedtls_printf( " failed\n ! mbedtls_ctr_drbg_seed returned %d\n",
133 ret );
134 goto exit;
135 }
136
137 mbedtls_printf( "\n . Reading private key from rsa_priv.txt" );
138 fflush( stdout );
139
140 if( ( f = fopen( "rsa_priv.txt", "rb" ) ) == NULL )
141 {
142 mbedtls_printf( " failed\n ! Could not open rsa_priv.txt\n" \
143 " ! Please run rsa_genkey first\n\n" );
144 goto exit;
145 }
146
147 if( ( ret = mbedtls_mpi_read_file( &N , 16, f ) ) != 0 ||
148 ( ret = mbedtls_mpi_read_file( &E , 16, f ) ) != 0 ||
149 ( ret = mbedtls_mpi_read_file( &D , 16, f ) ) != 0 ||
150 ( ret = mbedtls_mpi_read_file( &P , 16, f ) ) != 0 ||
151 ( ret = mbedtls_mpi_read_file( &Q , 16, f ) ) != 0 ||
152 ( ret = mbedtls_mpi_read_file( &DP , 16, f ) ) != 0 ||
153 ( ret = mbedtls_mpi_read_file( &DQ , 16, f ) ) != 0 ||
154 ( ret = mbedtls_mpi_read_file( &QP , 16, f ) ) != 0 )
155 {
156 mbedtls_printf( " failed\n ! mbedtls_mpi_read_file returned %d\n\n",
157 ret );
158 fclose( f );
159 goto exit;
160 }
161 fclose( f );
162
163 if( ( ret = mbedtls_rsa_import( &rsa, &N, &P, &Q, &D, &E ) ) != 0 )
164 {
165 mbedtls_printf( " failed\n ! mbedtls_rsa_import returned %d\n\n",
166 ret );
167 goto exit;
168 }
169
170 if( ( ret = mbedtls_rsa_complete( &rsa ) ) != 0 )
171 {
172 mbedtls_printf( " failed\n ! mbedtls_rsa_complete returned %d\n\n",
173 ret );
174 goto exit;
175 }
176
177 /*
178 * Extract the RSA encrypted value from the text file
179 */
180 if( ( f = fopen( "result-enc.txt", "rb" ) ) == NULL )
181 {
182 mbedtls_printf( "\n ! Could not open %s\n\n", "result-enc.txt" );
183 goto exit;
184 }
185
186 i = 0;
187
188 while( fscanf( f, "%02X", &c ) > 0 &&
189 i < (int) sizeof( buf ) )
190 buf[i++] = (unsigned char) c;
191
192 fclose( f );
193
194 if( i != rsa.len )
195 {
196 mbedtls_printf( "\n ! Invalid RSA signature format\n\n" );
197 goto exit;
198 }
199
200 /*
201 * Decrypt the encrypted RSA data and print the result.
202 */
203 mbedtls_printf( "\n . Decrypting the encrypted data" );
204 fflush( stdout );
205
206 ret = mbedtls_rsa_pkcs1_decrypt( &rsa, mbedtls_ctr_drbg_random,
207 &ctr_drbg, MBEDTLS_RSA_PRIVATE, &i,
208 buf, result, 1024 );
209 if( ret != 0 )
210 {
211 mbedtls_printf( " failed\n ! mbedtls_rsa_pkcs1_decrypt returned %d\n\n",
212 ret );
213 goto exit;
214 }
215
216 mbedtls_printf( "\n . OK\n\n" );
217
218 mbedtls_printf( "The decrypted result is: '%s'\n\n", result );
219
220 exit_code = MBEDTLS_EXIT_SUCCESS;
221
222 exit:
223 mbedtls_ctr_drbg_free( &ctr_drbg );
224 mbedtls_entropy_free( &entropy );
225 mbedtls_rsa_free( &rsa );
226 mbedtls_mpi_free( &N ); mbedtls_mpi_free( &P ); mbedtls_mpi_free( &Q );
227 mbedtls_mpi_free( &D ); mbedtls_mpi_free( &E ); mbedtls_mpi_free( &DP );
228 mbedtls_mpi_free( &DQ ); mbedtls_mpi_free( &QP );
229
230 #if defined(_WIN32)
231 mbedtls_printf( " + Press Enter to exit this program.\n" );
232 fflush( stdout ); getchar();
233 #endif
234
235 mbedtls_exit( exit_code );
236 }
237 #endif /* MBEDTLS_BIGNUM_C && MBEDTLS_RSA_C && MBEDTLS_FS_IO */
238