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/*
* RSA simple decryption program
*
* Copyright The Mbed TLS Contributors
* 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.
*/
#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 != rsa.MBEDTLS_PRIVATE(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 );
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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