260 lines
6.2 KiB
C
260 lines
6.2 KiB
C
/*
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* Copyright (C) 2014 FH Bielefeld
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*
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* This file is part of a FH Bielefeld project.
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
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* MA 02110-1301 USA
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*/
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#include "context.h"
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#include "err.h"
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#include "rand.h"
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#include "poly.h"
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#include <stdio.h>
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#include <stdlib.h>
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#include <tompoly.h>
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#include <tommath.h>
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#include <math.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <fcntl.h>
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#include <unistd.h>
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/*
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* static declarations
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*/
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static mp_digit read_int_dev_random();
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static mp_digit read_int_dev_urandom();
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static mp_digit make_small_int(mp_digit random_int, int* sign);
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static mp_digit make_big_int(mp_digit random_int, int* sign);
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/**
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* Reads a single mp_digit out of /dev/random and returns this mp_digit
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*
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* @return the randomly chosen integer
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*/
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static mp_digit read_int_dev_random()
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{
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int random_data;
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mp_digit random_int;
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size_t randomDataLen = 0;
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random_data = open("/dev/random", O_RDONLY);
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while (randomDataLen < sizeof(random_int)) {
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ssize_t result = read(random_data,
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((char*) &random_int) + randomDataLen,
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(sizeof(random_int)) - randomDataLen);
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if (result < 0) {
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NTRU_ABORT("Unable to read /dev/random.\n");
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}
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randomDataLen += result;
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}
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close(random_data);
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return random_int;
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}
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/**
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* Reads a single mp_digit out of /dev/urandom and returns this mp_digit
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*
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* @return the randomly chosen integer
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*/
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static mp_digit read_int_dev_urandom()
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{
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int random_data;
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mp_digit random_int;
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ssize_t result;
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random_data = open("/dev/urandom", O_RDONLY);
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if ((result = read(random_data, &random_int, sizeof(random_int))) < 0)
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NTRU_ABORT("Unable to read /dev/urandom.\n");
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close(random_data);
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return random_int;
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}
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/**
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* Makes a small integer from the set {-1, 0, 1}
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* out of a randomly chosen integer.
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* A zero is signed positiv.
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*
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* @param random_int a randomly chosen mp_digit
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* @param sign a integer to store the sign (1==positiv)
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* @return random small integer from the set {-1, 0, 1}
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*/
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static mp_digit make_small_int(mp_digit random_int, int* sign)
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{
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random_int = random_int % 3;
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if (random_int == 1) {
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*sign = 0;
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} else if (random_int == 2) {
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random_int = 1;
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*sign = 1;
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} else {
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*sign = 0;
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}
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return random_int;
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}
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/**
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* Makes a big integer from the borders of BIG_RAND_MAX
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* and BIG_RAND_MIN out of a randomly chosen integer.
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*
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* @param random_int a randomly chosen mp_digit
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* @param sign a integer to store the sign (1==positiv)
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* @return random big integer from the borders of BIG_RAND_MAX and BIG_RAND_MIN
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*/
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static mp_digit make_big_int(mp_digit random_int, int* sign)
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{
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random_int = random_int % abs(BIG_RAND_MAX - BIG_RAND_MIN);
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if (random_int < BIG_RAND_MAX) {
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*sign = 1;
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} else if (random_int > BIG_RAND_MAX) {
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*sign = 0;
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random_int -= BIG_RAND_MAX;
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} else if (random_int == BIG_RAND_MAX) {
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random_int = abs(BIG_RAND_MIN);
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*sign = 0;
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} else {
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NTRU_ABORT("Error while parsing big random Integer.\n");
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}
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return random_int;
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}
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/**
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* Gets a random polynomial with coefficients
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* from the set {-1 ,0 ,1} using /dev/random.
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*
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* @param ctx the NTRU context
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* @return newly allocated polynomial, must be freed with delete_polynom()
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*/
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pb_poly *ntru_get_rnd_poly_small(ntru_context *ctx)
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{
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mp_int chara;
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init_integer(&chara);
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pb_poly *poly = malloc(sizeof(pb_poly));
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init_polynom_size(poly, &chara, ctx->N);
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mp_clear(&chara);
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for (unsigned int i = 0; i < ctx->N; i++) {
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int sign;
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mp_digit c = read_int_dev_random();
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c = make_small_int(c, &sign);
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mp_set(&(poly->terms[i]), c);
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if (sign == 1)
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poly->terms[i].sign = 1;
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}
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poly->used = ctx->N;
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pb_clamp(poly);
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return poly;
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}
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/**
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* Gets a random polynomial with coefficients
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* from the set {-1 ,0 ,1} using /dev/urandom.
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*
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* @param ctx the NTRU context
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* @return newly allocated polynomial, must be freed with delete_polynom()
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*/
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pb_poly *ntru_get_urnd_poly_small(ntru_context *ctx)
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{
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mp_int chara;
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init_integer(&chara);
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pb_poly *poly = malloc(sizeof(pb_poly));
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init_polynom_size(poly, &chara, ctx->N);
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mp_clear(&chara);
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for (unsigned int i = 0; i < ctx->N; i++) {
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int sign;
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mp_digit c = read_int_dev_urandom();
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c = make_small_int(c, &sign);
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mp_set(&(poly->terms[i]), c);
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if (sign == 1)
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poly->terms[i].sign = 1;
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}
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poly->used = ctx->N;
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pb_clamp(poly);
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return poly;
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}
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/**
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* Gets a random polynomial with coefficients
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* from the borders of BIG_RAND_MAX and
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* BIG_RAND_MIN using /dev/random.
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*
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* @param ctx the NTRU context
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* @return newly allocated polynomial, must be freed with delete_polynom()
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*/
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pb_poly *ntru_get_rnd_poly_big(ntru_context *ctx)
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{
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mp_int chara;
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init_integer(&chara);
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pb_poly *poly = malloc(sizeof(pb_poly));
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init_polynom_size(poly, &chara, ctx->N);
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mp_clear(&chara);
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for (unsigned int i = 0; i < ctx->N; i++) {
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int sign;
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mp_digit c = read_int_dev_random();
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c = make_big_int(c, &sign);
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mp_set(&(poly->terms[i]), c);
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if (sign == 1)
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poly->terms[i].sign = 1;
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}
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poly->used = ctx->N;
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pb_clamp(poly);
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return poly;
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}
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/**
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* Gets a random polynomial with coefficients
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* from the borders of BIG_RAND_MAX and
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* BIG_RAND_MIN using /dev/urandom.
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*
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* @param ctx the NTRU context
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* @return newly allocated polynomial, must be freed with delete_polynom()
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*/
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pb_poly *ntru_get_urnd_poly_big(ntru_context *ctx)
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{
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mp_int chara;
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init_integer(&chara);
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pb_poly *poly = malloc(sizeof(pb_poly));
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init_polynom_size(poly, &chara, ctx->N);
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mp_clear(&chara);
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for (unsigned int i = 0; i < ctx->N; i++) {
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int sign;
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mp_digit c = read_int_dev_urandom();
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c = make_big_int(c, &sign);
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mp_set(&(poly->terms[i]), c);
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if (sign == 1)
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poly->terms[i].sign = 1;
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}
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poly->used = ctx->N;
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pb_clamp(poly);
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return poly;
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}
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