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/*
* RSA simple decryption program
*
* Copyright The Mbed TLS Contributors
* SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
*/
#include "mbedtls/build_info.h"
#include "mbedtls/platform.h"
#if defined(MBEDTLS_BIGNUM_C) && defined(MBEDTLS_RSA_C) && \
defined(MBEDTLS_FS_IO) && defined(MBEDTLS_ENTROPY_C) && \
defined(MBEDTLS_CTR_DRBG_C)
#include "mbedtls/rsa.h"
#include "mbedtls/entropy.h"
#include "mbedtls/ctr_drbg.h"
#include <string.h>
#endif
#if !defined(MBEDTLS_BIGNUM_C) || !defined(MBEDTLS_RSA_C) || \
!defined(MBEDTLS_FS_IO) || !defined(MBEDTLS_ENTROPY_C) || \
!defined(MBEDTLS_CTR_DRBG_C)
int main(void)
{
mbedtls_printf("MBEDTLS_BIGNUM_C and/or MBEDTLS_RSA_C and/or "
"MBEDTLS_FS_IO and/or MBEDTLS_ENTROPY_C and/or "
"MBEDTLS_CTR_DRBG_C not defined.\n");
mbedtls_exit(0);
}
#else
int main(int argc, char *argv[])
{
FILE *f;
int ret = 1;
int exit_code = MBEDTLS_EXIT_FAILURE;
unsigned c;
size_t i;
mbedtls_rsa_context rsa;
mbedtls_mpi N, P, Q, D, E, DP, DQ, QP;
mbedtls_entropy_context entropy;
mbedtls_ctr_drbg_context ctr_drbg;
unsigned char result[1024];
unsigned char buf[512];
const char *pers = "rsa_decrypt";
((void) argv);
memset(result, 0, sizeof(result));
if (argc != 1) {
mbedtls_printf("usage: rsa_decrypt\n");
#if defined(_WIN32)
mbedtls_printf("\n");
#endif
mbedtls_exit(exit_code);
}
mbedtls_printf("\n . Seeding the random number generator...");
fflush(stdout);
mbedtls_rsa_init(&rsa);
mbedtls_ctr_drbg_init(&ctr_drbg);
mbedtls_entropy_init(&entropy);
mbedtls_mpi_init(&N); mbedtls_mpi_init(&P); mbedtls_mpi_init(&Q);
mbedtls_mpi_init(&D); mbedtls_mpi_init(&E); mbedtls_mpi_init(&DP);
mbedtls_mpi_init(&DQ); mbedtls_mpi_init(&QP);
ret = mbedtls_ctr_drbg_seed(&ctr_drbg, mbedtls_entropy_func,
&entropy, (const unsigned char *) pers,
strlen(pers));
if (ret != 0) {
mbedtls_printf(" failed\n ! mbedtls_ctr_drbg_seed returned %d\n",
ret);
goto exit;
}
mbedtls_printf("\n . Reading private key from rsa_priv.txt");
fflush(stdout);
if ((f = fopen("rsa_priv.txt", "rb")) == NULL) {
mbedtls_printf(" failed\n ! Could not open rsa_priv.txt\n" \
" ! Please run rsa_genkey first\n\n");
goto exit;
}
if ((ret = mbedtls_mpi_read_file(&N, 16, f)) != 0 ||
(ret = mbedtls_mpi_read_file(&E, 16, f)) != 0 ||
(ret = mbedtls_mpi_read_file(&D, 16, f)) != 0 ||
(ret = mbedtls_mpi_read_file(&P, 16, f)) != 0 ||
(ret = mbedtls_mpi_read_file(&Q, 16, f)) != 0 ||
(ret = mbedtls_mpi_read_file(&DP, 16, f)) != 0 ||
(ret = mbedtls_mpi_read_file(&DQ, 16, f)) != 0 ||
(ret = mbedtls_mpi_read_file(&QP, 16, f)) != 0) {
mbedtls_printf(" failed\n ! mbedtls_mpi_read_file returned %d\n\n",
ret);
fclose(f);
goto exit;
}
fclose(f);
if ((ret = mbedtls_rsa_import(&rsa, &N, &P, &Q, &D, &E)) != 0) {
mbedtls_printf(" failed\n ! mbedtls_rsa_import returned %d\n\n",
ret);
goto exit;
}
if ((ret = mbedtls_rsa_complete(&rsa)) != 0) {
mbedtls_printf(" failed\n ! mbedtls_rsa_complete returned %d\n\n",
ret);
goto exit;
}
/*
* Extract the RSA encrypted value from the text file
*/
if ((f = fopen("result-enc.txt", "rb")) == NULL) {
mbedtls_printf("\n ! Could not open %s\n\n", "result-enc.txt");
goto exit;
}
i = 0;
while (fscanf(f, "%02X", (unsigned int *) &c) > 0 &&
i < (int) sizeof(buf)) {
buf[i++] = (unsigned char) c;
}
fclose(f);
if (i != mbedtls_rsa_get_len(&rsa)) {
mbedtls_printf("\n ! Invalid RSA signature format\n\n");
goto exit;
}
/*
* Decrypt the encrypted RSA data and print the result.
*/
mbedtls_printf("\n . Decrypting the encrypted data");
fflush(stdout);
ret = mbedtls_rsa_pkcs1_decrypt(&rsa, mbedtls_ctr_drbg_random,
&ctr_drbg, &i,
buf, result, 1024);
if (ret != 0) {
mbedtls_printf(" failed\n ! mbedtls_rsa_pkcs1_decrypt returned %d\n\n",
ret);
goto exit;
}
mbedtls_printf("\n . OK\n\n");
mbedtls_printf("The decrypted result is: '%s'\n\n", result);
exit_code = MBEDTLS_EXIT_SUCCESS;
exit:
mbedtls_ctr_drbg_free(&ctr_drbg);
mbedtls_entropy_free(&entropy);
mbedtls_rsa_free(&rsa);
mbedtls_mpi_free(&N); mbedtls_mpi_free(&P); mbedtls_mpi_free(&Q);
mbedtls_mpi_free(&D); mbedtls_mpi_free(&E); mbedtls_mpi_free(&DP);
mbedtls_mpi_free(&DQ); mbedtls_mpi_free(&QP);
mbedtls_exit(exit_code);
}
#endif /* MBEDTLS_BIGNUM_C && MBEDTLS_RSA_C && MBEDTLS_FS_IO */
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