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
8 #include "mbedtls/build_info.h"
9
10 #include "mbedtls/platform.h"
11
12 #if defined(MBEDTLS_BIGNUM_C) && defined(MBEDTLS_RSA_C) && \
13 defined(MBEDTLS_FS_IO) && defined(MBEDTLS_ENTROPY_C) && \
14 defined(MBEDTLS_CTR_DRBG_C)
15 #include "mbedtls/rsa.h"
16 #include "mbedtls/entropy.h"
17 #include "mbedtls/ctr_drbg.h"
18
19 #include <string.h>
20
21 #endif
22
23 #if !defined(MBEDTLS_BIGNUM_C) || !defined(MBEDTLS_RSA_C) || \
24 !defined(MBEDTLS_FS_IO) || !defined(MBEDTLS_ENTROPY_C) || \
25 !defined(MBEDTLS_CTR_DRBG_C)
main(void)26 int main(void)
27 {
28 mbedtls_printf("MBEDTLS_BIGNUM_C and/or MBEDTLS_RSA_C and/or "
29 "MBEDTLS_FS_IO and/or MBEDTLS_ENTROPY_C and/or "
30 "MBEDTLS_CTR_DRBG_C not defined.\n");
31 mbedtls_exit(0);
32 }
33 #else
34
35
main(int argc,char * argv[])36 int main(int argc, char *argv[])
37 {
38 FILE *f;
39 int ret = 1;
40 int exit_code = MBEDTLS_EXIT_FAILURE;
41 unsigned c;
42 size_t i;
43 mbedtls_rsa_context rsa;
44 mbedtls_mpi N, P, Q, D, E, DP, DQ, QP;
45 mbedtls_entropy_context entropy;
46 mbedtls_ctr_drbg_context ctr_drbg;
47 unsigned char result[1024];
48 unsigned char buf[512];
49 const char *pers = "rsa_decrypt";
50 ((void) argv);
51
52 memset(result, 0, sizeof(result));
53
54 if (argc != 1) {
55 mbedtls_printf("usage: rsa_decrypt\n");
56
57 #if defined(_WIN32)
58 mbedtls_printf("\n");
59 #endif
60
61 mbedtls_exit(exit_code);
62 }
63
64 mbedtls_printf("\n . Seeding the random number generator...");
65 fflush(stdout);
66
67 mbedtls_rsa_init(&rsa);
68 mbedtls_ctr_drbg_init(&ctr_drbg);
69 mbedtls_entropy_init(&entropy);
70 mbedtls_mpi_init(&N); mbedtls_mpi_init(&P); mbedtls_mpi_init(&Q);
71 mbedtls_mpi_init(&D); mbedtls_mpi_init(&E); mbedtls_mpi_init(&DP);
72 mbedtls_mpi_init(&DQ); mbedtls_mpi_init(&QP);
73
74 ret = mbedtls_ctr_drbg_seed(&ctr_drbg, mbedtls_entropy_func,
75 &entropy, (const unsigned char *) pers,
76 strlen(pers));
77 if (ret != 0) {
78 mbedtls_printf(" failed\n ! mbedtls_ctr_drbg_seed returned %d\n",
79 ret);
80 goto exit;
81 }
82
83 mbedtls_printf("\n . Reading private key from rsa_priv.txt");
84 fflush(stdout);
85
86 if ((f = fopen("rsa_priv.txt", "rb")) == NULL) {
87 mbedtls_printf(" failed\n ! Could not open rsa_priv.txt\n" \
88 " ! Please run rsa_genkey first\n\n");
89 goto exit;
90 }
91
92 if ((ret = mbedtls_mpi_read_file(&N, 16, f)) != 0 ||
93 (ret = mbedtls_mpi_read_file(&E, 16, f)) != 0 ||
94 (ret = mbedtls_mpi_read_file(&D, 16, f)) != 0 ||
95 (ret = mbedtls_mpi_read_file(&P, 16, f)) != 0 ||
96 (ret = mbedtls_mpi_read_file(&Q, 16, f)) != 0 ||
97 (ret = mbedtls_mpi_read_file(&DP, 16, f)) != 0 ||
98 (ret = mbedtls_mpi_read_file(&DQ, 16, f)) != 0 ||
99 (ret = mbedtls_mpi_read_file(&QP, 16, f)) != 0) {
100 mbedtls_printf(" failed\n ! mbedtls_mpi_read_file returned %d\n\n",
101 ret);
102 fclose(f);
103 goto exit;
104 }
105 fclose(f);
106
107 if ((ret = mbedtls_rsa_import(&rsa, &N, &P, &Q, &D, &E)) != 0) {
108 mbedtls_printf(" failed\n ! mbedtls_rsa_import returned %d\n\n",
109 ret);
110 goto exit;
111 }
112
113 if ((ret = mbedtls_rsa_complete(&rsa)) != 0) {
114 mbedtls_printf(" failed\n ! mbedtls_rsa_complete returned %d\n\n",
115 ret);
116 goto exit;
117 }
118
119 /*
120 * Extract the RSA encrypted value from the text file
121 */
122 if ((f = fopen("result-enc.txt", "rb")) == NULL) {
123 mbedtls_printf("\n ! Could not open %s\n\n", "result-enc.txt");
124 goto exit;
125 }
126
127 i = 0;
128
129 while (fscanf(f, "%02X", (unsigned int *) &c) > 0 &&
130 i < (int) sizeof(buf)) {
131 buf[i++] = (unsigned char) c;
132 }
133
134 fclose(f);
135
136 if (i != mbedtls_rsa_get_len(&rsa)) {
137 mbedtls_printf("\n ! Invalid RSA signature format\n\n");
138 goto exit;
139 }
140
141 /*
142 * Decrypt the encrypted RSA data and print the result.
143 */
144 mbedtls_printf("\n . Decrypting the encrypted data");
145 fflush(stdout);
146
147 ret = mbedtls_rsa_pkcs1_decrypt(&rsa, mbedtls_ctr_drbg_random,
148 &ctr_drbg, &i,
149 buf, result, 1024);
150 if (ret != 0) {
151 mbedtls_printf(" failed\n ! mbedtls_rsa_pkcs1_decrypt returned %d\n\n",
152 ret);
153 goto exit;
154 }
155
156 mbedtls_printf("\n . OK\n\n");
157
158 mbedtls_printf("The decrypted result is: '%s'\n\n", result);
159
160 exit_code = MBEDTLS_EXIT_SUCCESS;
161
162 exit:
163 mbedtls_ctr_drbg_free(&ctr_drbg);
164 mbedtls_entropy_free(&entropy);
165 mbedtls_rsa_free(&rsa);
166 mbedtls_mpi_free(&N); mbedtls_mpi_free(&P); mbedtls_mpi_free(&Q);
167 mbedtls_mpi_free(&D); mbedtls_mpi_free(&E); mbedtls_mpi_free(&DP);
168 mbedtls_mpi_free(&DQ); mbedtls_mpi_free(&QP);
169
170 mbedtls_exit(exit_code);
171 }
172 #endif /* MBEDTLS_BIGNUM_C && MBEDTLS_RSA_C && MBEDTLS_FS_IO */
173
