270 lines
6.3 KiB
C
270 lines
6.3 KiB
C
/**
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* @file gmp_helper.c
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*
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* @brief Class with helper functions for gmp operations
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*
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*/
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/*
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* Copyright (C) 1999, 2000, 2001 Henry Spencer.
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* Copyright (C) 2005 Jan Hutter, Martin Willi
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* Hochschule fuer Technik Rapperswil
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the
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* Free Software Foundation; either version 2 of the License, or (at your
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* option) any later version. See <http://www.fsf.org/copyleft/gpl.txt>.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* for more details.
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*/
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#include <stdio.h>
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#include "gmp_helper.h"
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#include "allocator.h"
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#include "randomizer.h"
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/**
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* Number of times the probabilistic primality test is applied
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*/
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#define PRIMECHECK_ROUNDS 30
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/**
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* Private data of an gmp_helper_t object.
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*
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*/
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typedef struct private_gmp_helper_s private_gmp_helper_t;
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struct private_gmp_helper_s {
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/**
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* public gmp_helper_t interface
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*/
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gmp_helper_t public;
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};
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/**
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* Implements private_gmp_helper_t's chunk_to_mpz function.
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* See #private_gmp_helper_t.chunk_to_mpz for description.
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*/
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static void chunk_to_mpz(private_gmp_helper_t *this, mpz_t *mpz_value, chunk_t data)
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{
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size_t i;
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mpz_init_set_ui(*(mpz_value), 0);
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for (i = 0; i < data.len; i++)
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{
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mpz_mul_ui(*(mpz_value),*(mpz_value), 1 << 8);
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mpz_add_ui(*(mpz_value),*(mpz_value), data.ptr[i]);
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}
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}
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/**
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* Implements private_gmp_helper_t's mpz_to_chunk function.
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* See #private_gmp_helper_t.mpz_to_chunk for description.
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*/
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static status_t mpz_to_chunk (private_gmp_helper_t *this,mpz_t *mpz_value, chunk_t *data,size_t bytes)
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{
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mpz_t temp1, temp2;
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status_t status = SUCCESS;
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int i;
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chunk_t tmp_chunk;
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tmp_chunk.len = bytes;
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tmp_chunk.ptr = allocator_alloc(tmp_chunk.len);
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if (tmp_chunk.ptr == NULL)
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{
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allocator_free_chunk(tmp_chunk);
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return OUT_OF_RES;
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}
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/* free memory */
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memset(tmp_chunk.ptr,0,tmp_chunk.len);
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mpz_init(temp1);
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mpz_init(temp2);
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mpz_set(temp1, *mpz_value);
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for (i = tmp_chunk.len-1; i >= 0; i--)
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{
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tmp_chunk.ptr[i] = mpz_mdivmod_ui(temp2, NULL, temp1, 1 << 8);
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mpz_set(temp1, temp2);
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}
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if (mpz_sgn(temp1) != 0)
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{
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fprintf (stderr,"value %d\n",mpz_sgn(temp1));
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status = FAILED;
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}
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mpz_clear(temp1);
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mpz_clear(temp2);
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*data = tmp_chunk;
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if (status != SUCCESS)
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{
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allocator_free_chunk(tmp_chunk);
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}
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return status;
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}
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/**
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* Implements gmp_helper_t's init_prime function.
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* See #gmp_helper_t.init_prime for description.
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*/
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static status_t init_prime (private_gmp_helper_t *this, mpz_t *prime, int bytes)
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{
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randomizer_t *randomizer;
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chunk_t random_bytes;
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status_t status;
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randomizer = randomizer_create();
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if (randomizer == NULL)
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{
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return OUT_OF_RES;
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}
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/* TODO change to true random device ? */
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// status = randomizer->allocate_random_bytes(randomizer,bytes, &random_bytes);
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status = randomizer->allocate_pseudo_random_bytes(randomizer,bytes, &random_bytes);
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/* make sure most significant bit is set */
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random_bytes.ptr[0] = random_bytes.ptr[0] | 0x80;
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/* not needed anymore */
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randomizer->destroy(randomizer);
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if (status != SUCCESS)
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{
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return status;
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}
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/* convert chunk to mpz value */
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this->public.chunk_to_mpz(&(this->public),prime, random_bytes);
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/* chunk is not used anymore */
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allocator_free(random_bytes.ptr);
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random_bytes.ptr = NULL;
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/* composites are possible but should never occur */
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mpz_nextprime (*(prime),*(prime));
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return SUCCESS;
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}
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static status_t init_prime_fast (private_gmp_helper_t *this, mpz_t *prime, int bytes){
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randomizer_t *randomizer;
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chunk_t random_bytes;
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status_t status;
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unsigned long tries;
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size_t length;
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randomizer = randomizer_create();
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if (randomizer == NULL)
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{
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return OUT_OF_RES;
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}
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/* TODO change to true random device ? */
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// status = randomizer->allocate_random_bytes(randomizer,bytes, &random_bytes);
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status = randomizer->allocate_pseudo_random_bytes(randomizer,bytes, &random_bytes);
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/* make sure most significant bit is set */
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random_bytes.ptr[0] = random_bytes.ptr[0] | 0x80;
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/* not needed anymore */
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randomizer->destroy(randomizer);
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if (status != SUCCESS)
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{
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return status;
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}
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/* convert chunk to mpz value */
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this->public.chunk_to_mpz(&(this->public),prime, random_bytes);
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/* chunk is not used anymore */
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allocator_free(random_bytes.ptr);
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random_bytes.ptr = NULL;
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/* make value odd */
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if (mpz_fdiv_ui(*prime, 2) != 1)
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{
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/* make value odd */
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mpz_add_ui(*prime,*prime,1);
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}
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tries = 1;
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/* starting find a prime */
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while (!mpz_probab_prime_p(*prime, PRIMECHECK_ROUNDS))
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{
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/* not a prime, increase by 2 */
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mpz_add_ui(*prime, *prime, 2);
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tries++;
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}
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length = mpz_sizeinbase(*prime, 2);
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/* check bit length of primee */
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if ((length < (bytes * 8)) || (length > ((bytes * 8) + 1)))
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{
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return FAILED;
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}
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if (length == ((bytes * 8) + 1))
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{
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/* carry out occured! retry */
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mpz_clear(*prime);
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/* recursive call */
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return this->public.init_prime_fast(&(this->public),prime, bytes);
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}
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return SUCCESS;
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}
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/**
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* Implements gmp_helper_t's destroy function.
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* See #gmp_helper_t.destroy for description.
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*/
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static status_t destroy(private_gmp_helper_t *this)
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{
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allocator_free(this);
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return SUCCESS;
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}
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/*
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* Described in header
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*/
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gmp_helper_t *gmp_helper_create()
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{
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private_gmp_helper_t *this = allocator_alloc_thing(private_gmp_helper_t);
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if ((this == NULL))
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{
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return NULL;
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}
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/* public functions */
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this->public.destroy = (status_t (*)(gmp_helper_t *)) destroy;
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this->public.init_prime = (status_t (*) (gmp_helper_t *, mpz_t *, int)) init_prime;
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this->public.init_prime_fast = (status_t (*) (gmp_helper_t *, mpz_t *, int)) init_prime_fast;
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/* private functions */
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this->public.chunk_to_mpz = (void (*) (gmp_helper_t *,mpz_t *, chunk_t )) chunk_to_mpz;
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this->public.mpz_to_chunk = (status_t (*) (gmp_helper_t *,mpz_t *, chunk_t *,size_t )) mpz_to_chunk;
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return &(this->public);
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}
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