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/*
* Copyright (C) 2012 Tobias Brunner
* Copyright (C) 2008 Martin Willi
* 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 rng rng
* @{ @ingroup crypto
*/
#ifndef RNG_H_
#define RNG_H_
typedef enum rng_quality_t rng_quality_t;
typedef struct rng_t rng_t;
#include <library.h>
/**
* Quality of generated random bytes.
*/
enum rng_quality_t {
/** weak randomness, usable for nonces, IVs */
RNG_WEAK,
/** stronger randomness, usable for session keys */
RNG_STRONG,
/** true random key material */
RNG_TRUE,
};
/**
* enum name for rng_quality_t.
*/
extern enum_name_t *rng_quality_names;
/**
* Generic interface for random number generators.
*/
struct rng_t {
/**
* Generates random bytes and writes them in the buffer.
*
* @param len number of bytes to get
* @param buffer pointer where the generated bytes will be written
* @return TRUE if bytes successfully written
*/
bool (*get_bytes)(rng_t *this, size_t len,
uint8_t *buffer) __attribute__((warn_unused_result));
/**
* Generates random bytes and allocate space for them.
*
* @param len number of bytes to get
* @param chunk chunk which will hold generated bytes
* @return TRUE if allocation succeeded
*/
bool (*allocate_bytes)(rng_t *this, size_t len,
chunk_t *chunk) __attribute__((warn_unused_result));
/**
* Destroys a rng object.
*/
void (*destroy)(rng_t *this);
};
/**
* Wrapper around rng_t.get_bytes() ensuring that either all bytes or at least
* the first byte is not zero.
*
* @param rng rng_t object
* @param len number of bytes to get
* @param buffer pointer where the generated bytes will be written
* @param all TRUE if all bytes have to be non-zero, FALSE for first
* @return TRUE if bytes successfully written
*/
bool rng_get_bytes_not_zero(rng_t *rng, size_t len, uint8_t *buffer,
bool all) __attribute__((warn_unused_result));
/**
* Wrapper around rng_t.allocate_bytes() ensuring that either all bytes or at
* least the first byte is not zero.
*
* @param rng rng_t object
* @param len number of bytes to get
* @param chunk chunk that stores the generated bytes (allocated)
* @param all TRUE if all bytes have to be non-zero, FALSE for first
* @return TRUE if bytes successfully written
*/
bool rng_allocate_bytes_not_zero(rng_t *rng, size_t len, chunk_t *chunk,
bool all) __attribute__((warn_unused_result));
#endif /** RNG_H_ @}*/
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