/*
* csprng.c
* --------
* HAL interface to Cryptech CSPRNG.
*
* Authors: Joachim Strömbergson, Paul Selkirk, Rob Austein
* Copyright (c) 2014-2015, SUNET
*
* Redistribution and use in source and binary forms, with or
* without modification, are permitted provided that the following
* conditions are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. 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.
*
* 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 OWNER 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 <assert.h>
#include <stdint.h>
#include <stddef.h>
#include <stdio.h>
#include "hal.h"
#ifndef WAIT_FOR_CSPRNG_VALID
#define WAIT_FOR_CSPRNG_VALID 0
#endif
hal_error_t hal_get_random(void *buffer, const size_t length)
{
uint8_t temp[4], *buf = buffer;
hal_error_t err;
size_t i;
for (i = 0; i < length; i += 4) {
const int last = (length - i) < 4;
if (WAIT_FOR_CSPRNG_VALID && (err = hal_io_wait_valid(CSPRNG_ADDR_STATUS)) != HAL_OK)
return err;
if ((err = hal_io_read(CSPRNG_ADDR_RANDOM, (last ? temp : &buf[i]), 4)) != HAL_OK)
return err;
if (last)
for (; i < length; i++)
buf[i] = temp[i&3];
}
for (i = 0, buf = buffer; i < length; i++, buf++)
if (*buf != 0)
return HAL_OK;
return HAL_ERROR_CSPRNG_BROKEN;
}
/*
* "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:
*/
