1 /*
2 * RSA simple decryption program
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_exit exit
35 #define MBEDTLS_EXIT_SUCCESS EXIT_SUCCESS
36 #define MBEDTLS_EXIT_FAILURE EXIT_FAILURE
37 #endif
38
39 #if defined(MBEDTLS_BIGNUM_C) && defined(MBEDTLS_RSA_C) && \
40 defined(MBEDTLS_FS_IO) && defined(MBEDTLS_ENTROPY_C) && \
41 defined(MBEDTLS_CTR_DRBG_C)
42 #include "mbedtls/rsa.h"
43 #include "mbedtls/entropy.h"
44 #include "mbedtls/ctr_drbg.h"
45
46 #include <string.h>
47
48 #endif
49
50 #if !defined(MBEDTLS_BIGNUM_C) || !defined(MBEDTLS_RSA_C) || \
51 !defined(MBEDTLS_FS_IO) || !defined(MBEDTLS_ENTROPY_C) || \
52 !defined(MBEDTLS_CTR_DRBG_C)
main(void)53 int main( void )
54 {
55 mbedtls_printf("MBEDTLS_BIGNUM_C and/or MBEDTLS_RSA_C and/or "
56 "MBEDTLS_FS_IO and/or MBEDTLS_ENTROPY_C and/or "
57 "MBEDTLS_CTR_DRBG_C not defined.\n");
58 return( 0 );
59 }
60 #else
main(int argc,char * argv[])61 int main( int argc, char *argv[] )
62 {
63 FILE *f;
64 int return_val, exit_val, c;
65 size_t i;
66 mbedtls_rsa_context rsa;
67 mbedtls_entropy_context entropy;
68 mbedtls_ctr_drbg_context ctr_drbg;
69 unsigned char result[1024];
70 unsigned char buf[512];
71 const char *pers = "rsa_decrypt";
72 ((void) argv);
73
74 memset(result, 0, sizeof( result ) );
75 exit_val = MBEDTLS_EXIT_SUCCESS;
76
77 if( argc != 1 )
78 {
79 mbedtls_printf( "usage: rsa_decrypt\n" );
80
81 #if defined(_WIN32)
82 mbedtls_printf( "\n" );
83 #endif
84
85 mbedtls_exit( MBEDTLS_EXIT_FAILURE );
86 }
87
88 mbedtls_printf( "\n . Seeding the random number generator..." );
89 fflush( stdout );
90
91 mbedtls_ctr_drbg_init( &ctr_drbg );
92 mbedtls_entropy_init( &entropy );
93
94 return_val = mbedtls_ctr_drbg_seed( &ctr_drbg, mbedtls_entropy_func,
95 &entropy, (const unsigned char *) pers,
96 strlen( pers ) );
97 if( return_val != 0 )
98 {
99 exit_val = MBEDTLS_EXIT_FAILURE;
100 mbedtls_printf( " failed\n ! mbedtls_ctr_drbg_seed returned %d\n",
101 return_val );
102 goto exit;
103 }
104
105 mbedtls_printf( "\n . Reading private key from rsa_priv.txt" );
106 fflush( stdout );
107
108 if( ( f = fopen( "rsa_priv.txt", "rb" ) ) == NULL )
109 {
110 exit_val = MBEDTLS_EXIT_FAILURE;
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( ( return_val = mbedtls_mpi_read_file( &rsa.N , 16, f ) ) != 0 ||
117 ( return_val = mbedtls_mpi_read_file( &rsa.E , 16, f ) ) != 0 ||
118 ( return_val = mbedtls_mpi_read_file( &rsa.D , 16, f ) ) != 0 ||
119 ( return_val = mbedtls_mpi_read_file( &rsa.P , 16, f ) ) != 0 ||
120 ( return_val = mbedtls_mpi_read_file( &rsa.Q , 16, f ) ) != 0 ||
121 ( return_val = mbedtls_mpi_read_file( &rsa.DP, 16, f ) ) != 0 ||
122 ( return_val = mbedtls_mpi_read_file( &rsa.DQ, 16, f ) ) != 0 ||
123 ( return_val = mbedtls_mpi_read_file( &rsa.QP, 16, f ) ) != 0 )
124 {
125 exit_val = MBEDTLS_EXIT_FAILURE;
126 mbedtls_printf( " failed\n ! mbedtls_mpi_read_file returned %d\n\n",
127 return_val );
128 fclose( f );
129 goto exit;
130 }
131
132 rsa.len = ( mbedtls_mpi_bitlen( &rsa.N ) + 7 ) >> 3;
133
134 fclose( f );
135
136 /*
137 * Extract the RSA encrypted value from the text file
138 */
139 if( ( f = fopen( "result-enc.txt", "rb" ) ) == NULL )
140 {
141 exit_val = MBEDTLS_EXIT_FAILURE;
142 mbedtls_printf( "\n ! Could not open %s\n\n", "result-enc.txt" );
143 goto exit;
144 }
145
146 i = 0;
147
148 while( fscanf( f, "%02X", &c ) > 0 &&
149 i < (int) sizeof( buf ) )
150 buf[i++] = (unsigned char) c;
151
152 fclose( f );
153
154 if( i != rsa.len )
155 {
156 exit_val = MBEDTLS_EXIT_FAILURE;
157 mbedtls_printf( "\n ! Invalid RSA signature format\n\n" );
158 goto exit;
159 }
160
161 /*
162 * Decrypt the encrypted RSA data and print the result.
163 */
164 mbedtls_printf( "\n . Decrypting the encrypted data" );
165 fflush( stdout );
166
167 return_val = mbedtls_rsa_pkcs1_decrypt( &rsa, mbedtls_ctr_drbg_random,
168 &ctr_drbg, MBEDTLS_RSA_PRIVATE, &i,
169 buf, result, 1024 );
170 if( return_val != 0 )
171 {
172 exit_val = MBEDTLS_EXIT_FAILURE;
173 mbedtls_printf( " failed\n ! mbedtls_rsa_pkcs1_decrypt returned %d\n\n",
174 return_val );
175 goto exit;
176 }
177
178 mbedtls_printf( "\n . OK\n\n" );
179
180 mbedtls_printf( "The decrypted result is: '%s'\n\n", result );
181
182 exit:
183 mbedtls_ctr_drbg_free( &ctr_drbg );
184 mbedtls_entropy_free( &entropy );
185 mbedtls_rsa_free( &rsa );
186
187 #if defined(_WIN32)
188 mbedtls_printf( " + Press Enter to exit this program.\n" );
189 fflush( stdout ); getchar();
190 #endif
191
192 return( exit_val );
193 }
194 #endif /* MBEDTLS_BIGNUM_C && MBEDTLS_RSA_C && MBEDTLS_FS_IO */
195
196
