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RAND: basic randomization

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No sanity checks like minimum number of non-NULL coefficients
for the polynomial.
This commit is contained in:
hasufell 2014-04-14 22:29:36 +02:00
parent 2029e91c47
commit ff40048d55
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GPG Key ID: 220CD1C5BDEED020
2 changed files with 132 additions and 0 deletions
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97
src/rand.c Normal file
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/*
* Copyright (C) 2014 hasufell
*
* This file is part of a hasufell project.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
* MA 02110-1301 USA
*/
#include "context.h"
#include "err.h"
#include "rand.h"
#include "poly.h"
#include <stdio.h>
#include <stdlib.h>
#include <tompoly.h>
#include <tommath.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
/**
* Gets randomly a small integer
* from the set {-1, 0, 1} using /dev/urandom.
*
* @param sign stores the signness [out]
* @return random small integer
*/
mp_digit get_urnd_int_small(int *sign)
{
int random_data;
mp_digit random_int;
ssize_t result;
random_data = open("/dev/urandom", O_RDONLY);
if ((result = read(random_data, &random_int, sizeof(random_int))) < 0)
NTRU_ABORT("Unable to read /dev/urandom");
close(random_int);
if ((random_int % 2) == 0) {
random_int = 0;
*sign = 0;
} else if (random_int % 3) {
random_int = 1;
*sign = 1;
} else {
random_int = 1;
*sign = 0;
}
return random_int;
}
/**
* Gets a random polynomial with coefficients
* from the set {-1 ,0 ,1} using /dev/urandom.
*
* @param ctx the NTRU context
* @return newly allocated polynomial
*/
pb_poly *get_urnd_poly_small(pqc_context *ctx)
{
mp_int *chara = malloc(sizeof(mp_int));
init_integer(chara);
pb_poly *poly = malloc(sizeof(pb_poly));
init_polynom_size(poly, chara, ctx->N);
for (int i = 0; i < ctx->N; i++) {
int sign;
int c = get_urnd_int_small(&sign);
mp_set(&(poly->terms[i]), (mp_digit)c);
if (sign == 1)
poly->terms[i].sign = 1;
}
poly->used = ctx->N;
pb_clamp(poly);
return poly;
}

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/*
* Copyright (C) 2014 hasufell
*
* This file is part of a hasufell project.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
* MA 02110-1301 USA
*/
#ifndef NTRU_RAND_H
#define NTRU_RAND_H
#include "context.h"
#include <tompoly.h>
mp_digit get_urnd_int_small(int *sign);
pb_poly *get_urnd_poly_small(pqc_context *ctx);
#endif /* NTRU_RAND_H */