mbedtls/programs/pkey/dh_genprime.c
2013-11-22 21:16:10 +01:00

159 lines
4.7 KiB
C

/*
* Diffie-Hellman-Merkle key exchange (prime generation)
*
* Copyright (C) 2006-2012, Brainspark B.V.
*
* This file is part of PolarSSL (http://www.polarssl.org)
* Lead Maintainer: Paul Bakker <polarssl_maintainer at polarssl.org>
*
* All rights reserved.
*
* 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.
*/
#include "polarssl/config.h"
#include <stdio.h>
#include "polarssl/bignum.h"
#include "polarssl/entropy.h"
#include "polarssl/ctr_drbg.h"
/*
* Note: G = 4 is always a quadratic residue mod P,
* so it is a generator of order Q (with P = 2*Q+1).
*/
#define DH_P_SIZE 1024
#define GENERATOR "4"
#if !defined(POLARSSL_BIGNUM_C) || !defined(POLARSSL_ENTROPY_C) || \
!defined(POLARSSL_FS_IO) || !defined(POLARSSL_CTR_DRBG_C) || \
!defined(POLARSSL_GENPRIME)
int main( int argc, char *argv[] )
{
((void) argc);
((void) argv);
printf("POLARSSL_BIGNUM_C and/or POLARSSL_ENTROPY_C and/or "
"POLARSSL_FS_IO and/or POLARSSL_CTR_DRBG_C and/or "
"POLARSSL_GENPRIME not defined.\n");
return( 0 );
}
#else
int main( int argc, char *argv[] )
{
int ret = 1;
mpi G, P, Q;
entropy_context entropy;
ctr_drbg_context ctr_drbg;
const char *pers = "dh_genprime";
FILE *fout;
((void) argc);
((void) argv);
mpi_init( &G ); mpi_init( &P ); mpi_init( &Q );
mpi_read_string( &G, 10, GENERATOR );
printf( "\nWARNING: You should not generate and use your own DHM primes\n" );
printf( " unless you are very certain of what you are doing!\n" );
printf( " Failing to follow this instruction may result in\n" );
printf( " weak security for your connections! Use the\n" );
printf( " predefined DHM parameters from dhm.h instead!\n\n" );
printf( "============================================================\n\n" );
printf( " ! Generating large primes may take minutes!\n" );
printf( "\n . Seeding the random number generator..." );
fflush( stdout );
entropy_init( &entropy );
if( ( ret = ctr_drbg_init( &ctr_drbg, entropy_func, &entropy,
(const unsigned char *) pers,
strlen( pers ) ) ) != 0 )
{
printf( " failed\n ! ctr_drbg_init returned %d\n", ret );
goto exit;
}
printf( " ok\n . Generating the modulus, please wait..." );
fflush( stdout );
/*
* This can take a long time...
*/
if( ( ret = mpi_gen_prime( &P, DH_P_SIZE, 1,
ctr_drbg_random, &ctr_drbg ) ) != 0 )
{
printf( " failed\n ! mpi_gen_prime returned %d\n\n", ret );
goto exit;
}
printf( " ok\n . Verifying that Q = (P-1)/2 is prime..." );
fflush( stdout );
if( ( ret = mpi_sub_int( &Q, &P, 1 ) ) != 0 )
{
printf( " failed\n ! mpi_sub_int returned %d\n\n", ret );
goto exit;
}
if( ( ret = mpi_div_int( &Q, NULL, &Q, 2 ) ) != 0 )
{
printf( " failed\n ! mpi_div_int returned %d\n\n", ret );
goto exit;
}
if( ( ret = mpi_is_prime( &Q, ctr_drbg_random, &ctr_drbg ) ) != 0 )
{
printf( " failed\n ! mpi_is_prime returned %d\n\n", ret );
goto exit;
}
printf( " ok\n . Exporting the value in dh_prime.txt..." );
fflush( stdout );
if( ( fout = fopen( "dh_prime.txt", "wb+" ) ) == NULL )
{
ret = 1;
printf( " failed\n ! Could not create dh_prime.txt\n\n" );
goto exit;
}
if( ( ret = mpi_write_file( "P = ", &P, 16, fout ) != 0 ) ||
( ret = mpi_write_file( "G = ", &G, 16, fout ) != 0 ) )
{
printf( " failed\n ! mpi_write_file returned %d\n\n", ret );
goto exit;
}
printf( " ok\n\n" );
fclose( fout );
exit:
mpi_free( &G ); mpi_free( &P ); mpi_free( &Q );
entropy_free( &entropy );
#if defined(_WIN32)
printf( " Press Enter to exit this program.\n" );
fflush( stdout ); getchar();
#endif
return( ret );
}
#endif /* POLARSSL_BIGNUM_C && POLARSSL_ENTROPY_C && POLARSSL_FS_IO &&
POLARSSL_CTR_DRBG_C && POLARSSL_GENPRIME */