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