programs/pkey/mpi_demo.c

/*
 *  Simple MPI demonstration program
 *
 *  Copyright (C) 2006-2011, ARM Limited, All Rights Reserved
 *
 *  This file is part of mbed TLS (https://polarssl.org)
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License along
 *  with this program; if not, write to the Free Software Foundation, Inc.,
 *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */

#if !defined(POLARSSL_CONFIG_FILE)
#include "polarssl/config.h"
#else
#include POLARSSL_CONFIG_FILE
#endif

#if defined(POLARSSL_PLATFORM_C)
#include "polarssl/platform.h"
#else
#include <stdio.h>
#define polarssl_printf     printf
#endif

#if defined(POLARSSL_BIGNUM_C) && defined(POLARSSL_FS_IO)
#include "polarssl/bignum.h"

#include <stdio.h>
#endif

#if !defined(POLARSSL_BIGNUM_C) || !defined(POLARSSL_FS_IO)
int main( void )
{
    polarssl_printf("POLARSSL_BIGNUM_C and/or POLARSSL_FS_IO not defined.\n");
    return( 0 );
}
#else
int main( void )
{
    int ret;
    mpi E, P, Q, N, H, D, X, Y, Z;

    mpi_init( &E ); mpi_init( &P ); mpi_init( &Q ); mpi_init( &N );
    mpi_init( &H ); mpi_init( &D ); mpi_init( &X ); mpi_init( &Y );
    mpi_init( &Z );

    MPI_CHK( mpi_read_string( &P, 10, "2789" ) );
    MPI_CHK( mpi_read_string( &Q, 10, "3203" ) );
    MPI_CHK( mpi_read_string( &E, 10,  "257" ) );
    MPI_CHK( mpi_mul_mpi( &N, &P, &Q ) );

    polarssl_printf( "\n  Public key:\n\n" );
    MPI_CHK( mpi_write_file( "  N = ", &N, 10, NULL ) );
    MPI_CHK( mpi_write_file( "  E = ", &E, 10, NULL ) );

    polarssl_printf( "\n  Private key:\n\n" );
    MPI_CHK( mpi_write_file( "  P = ", &P, 10, NULL ) );
    MPI_CHK( mpi_write_file( "  Q = ", &Q, 10, NULL ) );

#if defined(POLARSSL_GENPRIME)
    MPI_CHK( mpi_sub_int( &P, &P, 1 ) );
    MPI_CHK( mpi_sub_int( &Q, &Q, 1 ) );
    MPI_CHK( mpi_mul_mpi( &H, &P, &Q ) );
    MPI_CHK( mpi_inv_mod( &D, &E, &H ) );

    mpi_write_file( "  D = E^-1 mod (P-1)*(Q-1) = ",
                    &D, 10, NULL );
#else
    polarssl_printf("\nTest skipped (POLARSSL_GENPRIME not defined).\n\n");
#endif
    MPI_CHK( mpi_read_string( &X, 10, "55555" ) );
    MPI_CHK( mpi_exp_mod( &Y, &X, &E, &N, NULL ) );
    MPI_CHK( mpi_exp_mod( &Z, &Y, &D, &N, NULL ) );

    polarssl_printf( "\n  RSA operation:\n\n" );
    MPI_CHK( mpi_write_file( "  X (plaintext)  = ", &X, 10, NULL ) );
    MPI_CHK( mpi_write_file( "  Y (ciphertext) = X^E mod N = ", &Y, 10, NULL ) );
    MPI_CHK( mpi_write_file( "  Z (decrypted)  = Y^D mod N = ", &Z, 10, NULL ) );
    polarssl_printf( "\n" );

cleanup:
    mpi_free( &E ); mpi_free( &P ); mpi_free( &Q ); mpi_free( &N );
    mpi_free( &H ); mpi_free( &D ); mpi_free( &X ); mpi_free( &Y );
    mpi_free( &Z );

    if( ret != 0 )
    {
        polarssl_printf( "\nAn error occured.\n" );
        ret = 1;
    }

#if defined(_WIN32)
    polarssl_printf( "  Press Enter to exit this program.\n" );
    fflush( stdout ); getchar();
#endif

    return( ret );
}
#endif /* POLARSSL_BIGNUM_C && POLARSSL_FS_IO */