1 /*
2 * RSA simple decryption program
3 *
4 * Copyright The Mbed TLS Contributors
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
20 #if !defined(MBEDTLS_CONFIG_FILE)
21 #include "mbedtls/config.h"
22 #else
23 #include MBEDTLS_CONFIG_FILE
24 #endif
25
26 #if defined(MBEDTLS_PLATFORM_C)
27 #include "mbedtls/platform.h"
28 #else
29 #include <stdio.h>
30 #include <stdlib.h>
31 #define mbedtls_printf printf
32 #define mbedtls_exit exit
33 #define MBEDTLS_EXIT_SUCCESS EXIT_SUCCESS
34 #define MBEDTLS_EXIT_FAILURE EXIT_FAILURE
35 #endif /* MBEDTLS_PLATFORM_C */
36
37 #if defined(MBEDTLS_BIGNUM_C) && defined(MBEDTLS_RSA_C) && \
38 defined(MBEDTLS_FS_IO) && defined(MBEDTLS_ENTROPY_C) && \
39 defined(MBEDTLS_CTR_DRBG_C)
40 #include "mbedtls/rsa.h"
41 #include "mbedtls/entropy.h"
42 #include "mbedtls/ctr_drbg.h"
43
44 #include <string.h>
45
46 #endif
47
48 #if !defined(MBEDTLS_BIGNUM_C) || !defined(MBEDTLS_RSA_C) || \
49 !defined(MBEDTLS_FS_IO) || !defined(MBEDTLS_ENTROPY_C) || \
50 !defined(MBEDTLS_CTR_DRBG_C)
main(void)51 int main( void )
52 {
53 mbedtls_printf("MBEDTLS_BIGNUM_C and/or MBEDTLS_RSA_C and/or "
54 "MBEDTLS_FS_IO and/or MBEDTLS_ENTROPY_C and/or "
55 "MBEDTLS_CTR_DRBG_C not defined.\n");
56 mbedtls_exit( 0 );
57 }
58 #else
59
60
main(int argc,char * argv[])61 int main( int argc, char *argv[] )
62 {
63 FILE *f;
64 int ret = 1;
65 int exit_code = MBEDTLS_EXIT_FAILURE;
66 unsigned c;
67 size_t i;
68 mbedtls_rsa_context rsa;
69 mbedtls_mpi N, P, Q, D, E, DP, DQ, QP;
70 mbedtls_entropy_context entropy;
71 mbedtls_ctr_drbg_context ctr_drbg;
72 unsigned char result[1024];
73 unsigned char buf[512];
74 const char *pers = "rsa_decrypt";
75 ((void) argv);
76
77 memset(result, 0, sizeof( result ) );
78
79 if( argc != 1 )
80 {
81 mbedtls_printf( "usage: rsa_decrypt\n" );
82
83 #if defined(_WIN32)
84 mbedtls_printf( "\n" );
85 #endif
86
87 mbedtls_exit( exit_code );
88 }
89
90 mbedtls_printf( "\n . Seeding the random number generator..." );
91 fflush( stdout );
92
93 mbedtls_rsa_init( &rsa, MBEDTLS_RSA_PKCS_V15, 0 );
94 mbedtls_ctr_drbg_init( &ctr_drbg );
95 mbedtls_entropy_init( &entropy );
96 mbedtls_mpi_init( &N ); mbedtls_mpi_init( &P ); mbedtls_mpi_init( &Q );
97 mbedtls_mpi_init( &D ); mbedtls_mpi_init( &E ); mbedtls_mpi_init( &DP );
98 mbedtls_mpi_init( &DQ ); mbedtls_mpi_init( &QP );
99
100 ret = mbedtls_ctr_drbg_seed( &ctr_drbg, mbedtls_entropy_func,
101 &entropy, (const unsigned char *) pers,
102 strlen( pers ) );
103 if( ret != 0 )
104 {
105 mbedtls_printf( " failed\n ! mbedtls_ctr_drbg_seed returned %d\n",
106 ret );
107 goto exit;
108 }
109
110 mbedtls_printf( "\n . Reading private key from rsa_priv.txt" );
111 fflush( stdout );
112
113 if( ( f = fopen( "rsa_priv.txt", "rb" ) ) == NULL )
114 {
115 mbedtls_printf( " failed\n ! Could not open rsa_priv.txt\n" \
116 " ! Please run rsa_genkey first\n\n" );
117 goto exit;
118 }
119
120 if( ( ret = mbedtls_mpi_read_file( &N , 16, f ) ) != 0 ||
121 ( ret = mbedtls_mpi_read_file( &E , 16, f ) ) != 0 ||
122 ( ret = mbedtls_mpi_read_file( &D , 16, f ) ) != 0 ||
123 ( ret = mbedtls_mpi_read_file( &P , 16, f ) ) != 0 ||
124 ( ret = mbedtls_mpi_read_file( &Q , 16, f ) ) != 0 ||
125 ( ret = mbedtls_mpi_read_file( &DP , 16, f ) ) != 0 ||
126 ( ret = mbedtls_mpi_read_file( &DQ , 16, f ) ) != 0 ||
127 ( ret = mbedtls_mpi_read_file( &QP , 16, f ) ) != 0 )
128 {
129 mbedtls_printf( " failed\n ! mbedtls_mpi_read_file returned %d\n\n",
130 ret );
131 fclose( f );
132 goto exit;
133 }
134 fclose( f );
135
136 if( ( ret = mbedtls_rsa_import( &rsa, &N, &P, &Q, &D, &E ) ) != 0 )
137 {
138 mbedtls_printf( " failed\n ! mbedtls_rsa_import returned %d\n\n",
139 ret );
140 goto exit;
141 }
142
143 if( ( ret = mbedtls_rsa_complete( &rsa ) ) != 0 )
144 {
145 mbedtls_printf( " failed\n ! mbedtls_rsa_complete returned %d\n\n",
146 ret );
147 goto exit;
148 }
149
150 /*
151 * Extract the RSA encrypted value from the text file
152 */
153 if( ( f = fopen( "result-enc.txt", "rb" ) ) == NULL )
154 {
155 mbedtls_printf( "\n ! Could not open %s\n\n", "result-enc.txt" );
156 goto exit;
157 }
158
159 i = 0;
160
161 while( fscanf( f, "%02X", (unsigned int*) &c ) > 0 &&
162 i < (int) sizeof( buf ) )
163 buf[i++] = (unsigned char) c;
164
165 fclose( f );
166
167 if( i != rsa.len )
168 {
169 mbedtls_printf( "\n ! Invalid RSA signature format\n\n" );
170 goto exit;
171 }
172
173 /*
174 * Decrypt the encrypted RSA data and print the result.
175 */
176 mbedtls_printf( "\n . Decrypting the encrypted data" );
177 fflush( stdout );
178
179 ret = mbedtls_rsa_pkcs1_decrypt( &rsa, mbedtls_ctr_drbg_random,
180 &ctr_drbg, MBEDTLS_RSA_PRIVATE, &i,
181 buf, result, 1024 );
182 if( ret != 0 )
183 {
184 mbedtls_printf( " failed\n ! mbedtls_rsa_pkcs1_decrypt returned %d\n\n",
185 ret );
186 goto exit;
187 }
188
189 mbedtls_printf( "\n . OK\n\n" );
190
191 mbedtls_printf( "The decrypted result is: '%s'\n\n", result );
192
193 exit_code = MBEDTLS_EXIT_SUCCESS;
194
195 exit:
196 mbedtls_ctr_drbg_free( &ctr_drbg );
197 mbedtls_entropy_free( &entropy );
198 mbedtls_rsa_free( &rsa );
199 mbedtls_mpi_free( &N ); mbedtls_mpi_free( &P ); mbedtls_mpi_free( &Q );
200 mbedtls_mpi_free( &D ); mbedtls_mpi_free( &E ); mbedtls_mpi_free( &DP );
201 mbedtls_mpi_free( &DQ ); mbedtls_mpi_free( &QP );
202
203 #if defined(_WIN32)
204 mbedtls_printf( " + Press Enter to exit this program.\n" );
205 fflush( stdout ); getchar();
206 #endif
207
208 mbedtls_exit( exit_code );
209 }
210 #endif /* MBEDTLS_BIGNUM_C && MBEDTLS_RSA_C && MBEDTLS_FS_IO */
211