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/*
* Copyright (C) 2014 Andreas Steffen
* HSR 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.
*/
/**
* @defgroup bliss_sampler bliss_sampler
* @{ @ingroup bliss_p
*/
#ifndef BLISS_SAMPLER_H_
#define BLISS_SAMPLER_H_
typedef struct bliss_sampler_t bliss_sampler_t;
#include "bliss_param_set.h"
#include <library.h>
#include <crypto/hashers/hasher.h>
/**
* Implementation various rejection sampling algorithms.
*/
struct bliss_sampler_t {
/**
* Sample according to exp(-x/(2*sigma^2))
*
* @param x Value to be sampled
* @param accepted TRUE if value is accepted, FALSE if rejected
* @result TRUE if sampling was successful
*/
bool (*bernoulli_exp)(bliss_sampler_t *this, uint32_t x, bool *accepted);
/**
* Sample according to 1/cosh(x/sigma^2)
*
* @param x Value to be sampled
* @param accepted TRUE if value is accepted, FALSE if rejected
* @result TRUE if sampling was successful
*/
bool (*bernoulli_cosh)(bliss_sampler_t *this, int32_t x, bool *accepted);
/**
* Sample according to 2^(-x^2) for positive x
*
* @param x Generated value
* @result TRUE if sampling was successful
*/
bool (*pos_binary)(bliss_sampler_t *this, uint32_t *x);
/**
* Sample according to the Gaussian distribution exp(-x^2/(2*sigma^2))
*
* @param z Generated value with Gaussian distribution
* @result TRUE if sampling was successful
*/
bool (*gaussian)(bliss_sampler_t *this, int32_t *z);
/**
* Sample the sign according to the binary distribution
*
* @param positive TRUE if positive
* @result TRUE if sampling was successful
*/
bool (*sign)(bliss_sampler_t *this, bool *positive);
/**
* Destroy bliss_sampler_t object
*/
void (*destroy)(bliss_sampler_t *this);
};
/**
* Create a bliss_sampler_t object.
*
* @param alg Hash algorithm to be used for the internal bitspender
* @param seed Seed used to initialize the internal bitspender
* @param set BLISS parameter set to be used
*/
bliss_sampler_t *bliss_sampler_create(hash_algorithm_t alg, chunk_t seed,
bliss_param_set_t *set);
#endif /** BLISS_SAMPLER_H_ @}*/
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