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/**
* @file gmp_helper.c
*
* @brief Implementation of gmp_helper_t.
*
*/
/*
* Copyright (C) 1999, 2000, 2001 Henry Spencer.
* Copyright (C) 2005 Jan Hutter, Martin Willi
* Hochschule fuer Technik Rapperswil
*
* 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. See <http://www.fsf.org/copyleft/gpl.txt>.
*
* 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.
*/
#include <stdio.h>
#include "gmp_helper.h"
#include <utils/allocator.h>
#include <utils/randomizer.h>
/**
* Number of times the probabilistic primality test is applied.
*/
#define PRIMECHECK_ROUNDS 30
typedef struct private_gmp_helper_t private_gmp_helper_t;
/**
* Private data of an gmp_helper_t object.
*/
struct private_gmp_helper_t {
/**
* Public gmp_helper_t interface.
*/
gmp_helper_t public;
};
/**
* Implementation of gmp_helper_t.chunk_to_mpz.
*/
static void chunk_to_mpz(private_gmp_helper_t *this, mpz_t *mpz_value, chunk_t data)
{
size_t i;
mpz_init_set_ui(*(mpz_value), 0);
for (i = 0; i < data.len; i++)
{
mpz_mul_ui(*(mpz_value),*(mpz_value), 1 << 8);
mpz_add_ui(*(mpz_value),*(mpz_value), data.ptr[i]);
}
}
/**
* Implementation of gmp_helper_t.mpz_to_chunk.
*/
static void mpz_to_chunk (private_gmp_helper_t *this,mpz_t *mpz_value, chunk_t *data,size_t bytes)
{
mpz_t temp1, temp2;
int i;
chunk_t tmp_chunk;
tmp_chunk.len = bytes;
tmp_chunk.ptr = allocator_alloc(tmp_chunk.len);
memset(tmp_chunk.ptr,0,tmp_chunk.len);
mpz_init(temp1);
mpz_init(temp2);
mpz_set(temp1, *mpz_value);
for (i = tmp_chunk.len-1; i >= 0; i--)
{
tmp_chunk.ptr[i] = mpz_mdivmod_ui(temp2, NULL, temp1, 1 << 8);
mpz_set(temp1, temp2);
}
mpz_clear(temp1);
mpz_clear(temp2);
*data = tmp_chunk;
}
/**
* Implementation of gmp_helper_t.init_prime.
*/
static void init_prime (private_gmp_helper_t *this, mpz_t *prime, int bytes)
{
randomizer_t *randomizer;
chunk_t random_bytes;
randomizer = randomizer_create();
/* TODO change to true random device ? */
//randomizer->allocate_random_bytes(randomizer,bytes, &random_bytes);
randomizer->allocate_pseudo_random_bytes(randomizer,bytes, &random_bytes);
/* make sure most significant bit is set */
random_bytes.ptr[0] = random_bytes.ptr[0] | 0x80;
/* not needed anymore */
randomizer->destroy(randomizer);
/* convert chunk to mpz value */
this->public.chunk_to_mpz(&(this->public),prime, random_bytes);
/* chunk is not used anymore */
allocator_free(random_bytes.ptr);
random_bytes.ptr = NULL;
/* composites are possible but should never occur */
mpz_nextprime (*(prime),*(prime));
}
/**
* Implementation of gmp_helper_t.destroy.
*/
static void destroy(private_gmp_helper_t *this)
{
allocator_free(this);
}
/*
* Described in header
*/
gmp_helper_t *gmp_helper_create()
{
private_gmp_helper_t *this = allocator_alloc_thing(private_gmp_helper_t);
/* public functions */
this->public.destroy = (void (*)(gmp_helper_t *)) destroy;
this->public.init_prime = (void (*) (gmp_helper_t *, mpz_t *, int)) init_prime;
/* private functions */
this->public.chunk_to_mpz = (void (*) (gmp_helper_t *,mpz_t *, chunk_t )) chunk_to_mpz;
this->public.mpz_to_chunk = (void (*) (gmp_helper_t *,mpz_t *, chunk_t *,size_t )) mpz_to_chunk;
return &(this->public);
}
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