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/*
* Copyright (C) 2015 René Kijewski <rene.kijewski@fu-berlin.de>
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
/*
* Please notice:
* - I am not a cryptographer.
* - You should not use this code to run a nuclear power plant without a proper review.
*/
#include "crypto/chacha.h"
#include "mutex.h"
#include <string.h>
static chacha_ctx _chacha_prng_ctx = {
.state = { RIOT_CHACHA_PRNG_DEFAULT },
.rounds = 8,
};
static uint32_t _chacha_prng_data[64];
static signed _chacha_prng_pos = 0;
static mutex_t _chacha_prng_mutex = MUTEX_INIT;
void chacha_prng_seed(const void *data, size_t bytes)
{
mutex_lock(&_chacha_prng_mutex);
memcpy(_chacha_prng_ctx.state, data, bytes);
_chacha_prng_pos = 0;
mutex_unlock(&_chacha_prng_mutex);
}
uint32_t chacha_prng_next(void)
{
mutex_lock(&_chacha_prng_mutex);
if (--_chacha_prng_pos < 0) {
_chacha_prng_pos = 15;
chacha_keystream_bytes(&_chacha_prng_ctx, _chacha_prng_data);
}
uint32_t result = _chacha_prng_data[_chacha_prng_pos];
mutex_unlock(&_chacha_prng_mutex);
return result;
}