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/*
* csprng.c
* --------
* HAL interface to Cryptech CSPRNG.
*
* Authors: Joachim Strömbergson, Paul Selkirk, Rob Austein
* Copyright (c) 2014-2015, NORDUnet A/S
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
* - Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
*
* - Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* - Neither the name of the NORDUnet nor the names of its contributors may
* be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
* IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
* PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
* TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <stdint.h>
#include "hal.h"
#include "hal_internal.h"
#ifndef WAIT_FOR_CSPRNG_VALID
#define WAIT_FOR_CSPRNG_VALID 1
#endif
hal_error_t hal_get_random(hal_core_t *core, void *buffer, const size_t length)
{
uint8_t temp[4], ior = 0, * const buf = buffer;
const int free_core = core == NULL;
hal_error_t err = HAL_OK;
if (free_core && (err = hal_core_alloc(CSPRNG_NAME, &core, NULL)) != HAL_OK)
return err;
for (size_t i = 0; i < length; i += 4) {
const int last = (length - i) < 4;
if (WAIT_FOR_CSPRNG_VALID && (err = hal_io_wait_valid(core)) != HAL_OK)
break;
if ((err = hal_io_read(core, CSPRNG_ADDR_RANDOM, (last ? temp : &buf[i]), 4)) != HAL_OK)
break;
if (last)
for (; i < length; i++)
buf[i] = temp[i&3];
}
if (err == HAL_OK) {
for (size_t i = 0; i < length; i++)
ior |= buf[i];
if (ior == 0 && length > 0)
err = HAL_ERROR_CSPRNG_BROKEN;
}
if (free_core)
hal_core_free(core);
return err;
}
/*
* "Any programmer who fails to comply with the standard naming, formatting,
* or commenting conventions should be shot. If it so happens that it is
* inconvenient to shoot him, then he is to be politely requested to recode
* his program in adherence to the above standard."
* -- Michael Spier, Digital Equipment Corporation
*
* Local variables:
* indent-tabs-mode: nil
* End:
*/
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