Implemented Gaussian rejection sampler

The bliss_sampler class uses the mgf1_bitspender as a pseudo-random source.
2014-11-29 14:51:16 +01:00
parent 72bb7eec9c
commit edd72b6bb9
6 changed files with 496 additions and 16 deletions
@@ -0,0 +1,77 @@
+/*
+ * 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 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);
+
+	/**
+	 * 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_ @}*/