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