rsa_encrypt.c

/*
 *  RSA simple data encryption 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_ENTROPY_C) && defined(MBEDTLS_FS_IO) && \
    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_ENTROPY_C) || !defined(MBEDTLS_FS_IO) || \
    !defined(MBEDTLS_CTR_DRBG_C)
int main( void )
{
    mbedtls_printf("MBEDTLS_BIGNUM_C and/or MBEDTLS_RSA_C and/or "
           "MBEDTLS_ENTROPY_C and/or MBEDTLS_FS_IO 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;
    size_t i;
    mbedtls_rsa_context rsa;
    mbedtls_entropy_context entropy;
    mbedtls_ctr_drbg_context ctr_drbg;
    unsigned char input[1024];
    unsigned char buf[512];
    const char *pers = "rsa_encrypt";
    mbedtls_mpi N, E;

    if( argc != 2 )
    {
        mbedtls_printf( "usage: rsa_encrypt <string of max 100 characters>\n" );

#if defined(_WIN32)
        mbedtls_printf( "\n" );
#endif

        mbedtls_exit( exit_code );
    }

    mbedtls_printf( "\n  . Seeding the random number generator..." );
    fflush( stdout );

    mbedtls_mpi_init( &N ); mbedtls_mpi_init( &E );
    mbedtls_rsa_init( &rsa );
    mbedtls_ctr_drbg_init( &ctr_drbg );
    mbedtls_entropy_init( &entropy );

    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 public key from rsa_pub.txt" );
    fflush( stdout );

    if( ( f = fopen( "rsa_pub.txt", "rb" ) ) == NULL )
    {
        mbedtls_printf( " failed\n  ! Could not open rsa_pub.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 )
    {
        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, NULL, NULL, NULL, &E ) ) != 0 )
    {
        mbedtls_printf( " failed\n  ! mbedtls_rsa_import returned %d\n\n",
                        ret );
        goto exit;
    }

    if( strlen( argv[1] ) > 100 )
    {
        mbedtls_printf( " Input data larger than 100 characters.\n\n" );
        goto exit;
    }

    memcpy( input, argv[1], strlen( argv[1] ) );

    /*
     * Calculate the RSA encryption of the hash.
     */
    mbedtls_printf( "\n  . Generating the RSA encrypted value" );
    fflush( stdout );

    ret = mbedtls_rsa_pkcs1_encrypt( &rsa, mbedtls_ctr_drbg_random,
                                     &ctr_drbg, strlen( argv[1] ), input, buf );
    if( ret != 0 )
    {
        mbedtls_printf( " failed\n  ! mbedtls_rsa_pkcs1_encrypt returned %d\n\n",
                        ret );
        goto exit;
    }

    /*
     * Write the signature into result-enc.txt
     */
    if( ( f = fopen( "result-enc.txt", "wb+" ) ) == NULL )
    {
        mbedtls_printf( " failed\n  ! Could not create %s\n\n", "result-enc.txt" );
        goto exit;
    }

    for( i = 0; i < rsa.MBEDTLS_PRIVATE(len); i++ )
        mbedtls_fprintf( f, "%02X%s", buf[i],
                 ( i + 1 ) % 16 == 0 ? "\r\n" : " " );

    fclose( f );

    mbedtls_printf( "\n  . Done (created \"%s\")\n\n", "result-enc.txt" );

    exit_code = MBEDTLS_EXIT_SUCCESS;

exit:
    mbedtls_mpi_free( &N ); mbedtls_mpi_free( &E );
    mbedtls_ctr_drbg_free( &ctr_drbg );
    mbedtls_entropy_free( &entropy );
    mbedtls_rsa_free( &rsa );

    mbedtls_exit( exit_code );
}
#endif /* MBEDTLS_BIGNUM_C && MBEDTLS_RSA_C && MBEDTLS_ENTROPY_C &&
          MBEDTLS_FS_IO && MBEDTLS_CTR_DRBG_C */