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/*
* RSA simple decryption program
*
* Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
* SPDX-License-Identifier: Apache-2.0
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may
* not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
* This file is part of mbed TLS (https://tls.mbed.org)
*/
#if !defined(MBEDTLS_CONFIG_FILE)
#include "mbedtls/config.h"
#else
#include MBEDTLS_CONFIG_FILE
#endif
#if defined(MBEDTLS_PLATFORM_C)
#include "mbedtls/platform.h"
#else
#include <stdio.h>
#define mbedtls_printf printf
#endif
#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 <stdio.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");
return( 0 );
}
#else
int main( int argc, char *argv[] )
{
FILE *f;
int ret, c;
size_t i;
mbedtls_rsa_context rsa;
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 ) );
mbedtls_ctr_drbg_init( &ctr_drbg );
ret = 1;
if( argc != 1 )
{
mbedtls_printf( "usage: rsa_decrypt\n" );
#if defined(_WIN32)
mbedtls_printf( "\n" );
#endif
goto exit;
}
mbedtls_printf( "\n . Seeding the random number generator..." );
fflush( stdout );
mbedtls_entropy_init( &entropy );
if( ( ret = mbedtls_ctr_drbg_seed( &ctr_drbg, mbedtls_entropy_func, &entropy,
(const unsigned char *) pers,
strlen( pers ) ) ) != 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;
}
mbedtls_rsa_init( &rsa, MBEDTLS_RSA_PKCS_V15, 0 );
if( ( ret = mbedtls_mpi_read_file( &rsa.N , 16, f ) ) != 0 ||
( ret = mbedtls_mpi_read_file( &rsa.E , 16, f ) ) != 0 ||
( ret = mbedtls_mpi_read_file( &rsa.D , 16, f ) ) != 0 ||
( ret = mbedtls_mpi_read_file( &rsa.P , 16, f ) ) != 0 ||
( ret = mbedtls_mpi_read_file( &rsa.Q , 16, f ) ) != 0 ||
( ret = mbedtls_mpi_read_file( &rsa.DP, 16, f ) ) != 0 ||
( ret = mbedtls_mpi_read_file( &rsa.DQ, 16, f ) ) != 0 ||
( ret = mbedtls_mpi_read_file( &rsa.QP, 16, f ) ) != 0 )
{
mbedtls_printf( " failed\n ! mbedtls_mpi_read_file returned %d\n\n", ret );
goto exit;
}
rsa.len = ( mbedtls_mpi_bitlen( &rsa.N ) + 7 ) >> 3;
fclose( f );
/*
* Extract the RSA encrypted value from the text file
*/
ret = 1;
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", &c ) > 0 &&
i < (int) sizeof( buf ) )
buf[i++] = (unsigned char) c;
fclose( f );
if( i != rsa.len )
{
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 );
if( ( ret = mbedtls_rsa_pkcs1_decrypt( &rsa, mbedtls_ctr_drbg_random, &ctr_drbg,
MBEDTLS_RSA_PRIVATE, &i, buf, result,
1024 ) ) != 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 );
ret = 0;
exit:
mbedtls_ctr_drbg_free( &ctr_drbg );
mbedtls_entropy_free( &entropy );
#if defined(_WIN32)
mbedtls_printf( " + Press Enter to exit this program.\n" );
fflush( stdout ); getchar();
#endif
return( ret );
}
#endif /* MBEDTLS_BIGNUM_C && MBEDTLS_RSA_C && MBEDTLS_FS_IO */
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