1/*
2 *  RSA/SHA-256 signature verification 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/* md.h is included this early since MD_CAN_XXX macros are defined there. */
12#include "mbedtls/md.h"
13
14#if !defined(MBEDTLS_BIGNUM_C) || !defined(MBEDTLS_RSA_C) ||  \
15    !defined(MBEDTLS_MD_CAN_SHA256) || !defined(MBEDTLS_MD_C) || \
16    !defined(MBEDTLS_FS_IO)
17int main(void)
18{
19    mbedtls_printf("MBEDTLS_BIGNUM_C and/or MBEDTLS_RSA_C and/or "
20                   "MBEDTLS_MD_C and/or "
21                   "MBEDTLS_MD_CAN_SHA256 and/or MBEDTLS_FS_IO not defined.\n");
22    mbedtls_exit(0);
23}
24#else
25
26#include "mbedtls/rsa.h"
27
28#include <stdio.h>
29#include <string.h>
30
31
32int main(int argc, char *argv[])
33{
34    FILE *f;
35    int ret = 1;
36    unsigned c;
37    int exit_code = MBEDTLS_EXIT_FAILURE;
38    size_t i;
39    mbedtls_rsa_context rsa;
40    mbedtls_mpi N, E;
41    unsigned char hash[32];
42    unsigned char buf[MBEDTLS_MPI_MAX_SIZE];
43    char filename[512];
44
45    mbedtls_rsa_init(&rsa);
46    mbedtls_mpi_init(&N);
47    mbedtls_mpi_init(&E);
48
49    if (argc != 2) {
50        mbedtls_printf("usage: rsa_verify <filename>\n");
51
52#if defined(_WIN32)
53        mbedtls_printf("\n");
54#endif
55
56        goto exit;
57    }
58
59    mbedtls_printf("\n  . Reading public key from rsa_pub.txt");
60    fflush(stdout);
61
62    if ((f = fopen("rsa_pub.txt", "rb")) == NULL) {
63        mbedtls_printf(" failed\n  ! Could not open rsa_pub.txt\n" \
64                       "  ! Please run rsa_genkey first\n\n");
65        goto exit;
66    }
67
68    if ((ret = mbedtls_mpi_read_file(&N, 16, f)) != 0 ||
69        (ret = mbedtls_mpi_read_file(&E, 16, f)) != 0 ||
70        (ret = mbedtls_rsa_import(&rsa, &N, NULL, NULL, NULL, &E) != 0)) {
71        mbedtls_printf(" failed\n  ! mbedtls_mpi_read_file returned %d\n\n", ret);
72        fclose(f);
73        goto exit;
74    }
75    fclose(f);
76
77    /*
78     * Extract the RSA signature from the text file
79     */
80    mbedtls_snprintf(filename, sizeof(filename), "%s.sig", argv[1]);
81
82    if ((f = fopen(filename, "rb")) == NULL) {
83        mbedtls_printf("\n  ! Could not open %s\n\n", filename);
84        goto exit;
85    }
86
87    i = 0;
88    while (fscanf(f, "%02X", (unsigned int *) &c) > 0 &&
89           i < (int) sizeof(buf)) {
90        buf[i++] = (unsigned char) c;
91    }
92
93    fclose(f);
94
95    if (i != mbedtls_rsa_get_len(&rsa)) {
96        mbedtls_printf("\n  ! Invalid RSA signature format\n\n");
97        goto exit;
98    }
99
100    /*
101     * Compute the SHA-256 hash of the input file and
102     * verify the signature
103     */
104    mbedtls_printf("\n  . Verifying the RSA/SHA-256 signature");
105    fflush(stdout);
106
107    if ((ret = mbedtls_md_file(
108             mbedtls_md_info_from_type(MBEDTLS_MD_SHA256),
109             argv[1], hash)) != 0) {
110        mbedtls_printf(" failed\n  ! Could not open or read %s\n\n", argv[1]);
111        goto exit;
112    }
113
114    if ((ret = mbedtls_rsa_pkcs1_verify(&rsa, MBEDTLS_MD_SHA256,
115                                        32, hash, buf)) != 0) {
116        mbedtls_printf(" failed\n  ! mbedtls_rsa_pkcs1_verify returned -0x%0x\n\n",
117                       (unsigned int) -ret);
118        goto exit;
119    }
120
121    mbedtls_printf("\n  . OK (the signature is valid)\n\n");
122
123    exit_code = MBEDTLS_EXIT_SUCCESS;
124
125exit:
126
127    mbedtls_rsa_free(&rsa);
128    mbedtls_mpi_free(&N);
129    mbedtls_mpi_free(&E);
130
131    mbedtls_exit(exit_code);
132}
133#endif /* MBEDTLS_BIGNUM_C && MBEDTLS_RSA_C && MBEDTLS_MD_CAN_SHA256 &&
134          MBEDTLS_FS_IO */
135