mirror of
https://github.com/RIOT-OS/RIOT.git
synced 2024-12-29 04:50:03 +01:00
70 lines
1.8 KiB
C
70 lines
1.8 KiB
C
/*
|
|
* Copyright (C) 2018 HAW Hamburg
|
|
*
|
|
* This file is subject to the terms and conditions of the GNU Lesser
|
|
* General Public License v2.1. See the file LICENSE in the top level
|
|
* directory for more details.
|
|
*/
|
|
|
|
/**
|
|
* @ingroup sys_puf_sram
|
|
*
|
|
* @{
|
|
* @file
|
|
*
|
|
* @author Peter Kietzmann <peter.kietzmann@haw-hamburg.de>
|
|
*
|
|
* @}
|
|
*/
|
|
#include "cpu_conf.h"
|
|
#include "hashes.h"
|
|
#include "puf_sram.h"
|
|
|
|
/* Allocation of the PUF seed variable */
|
|
PUF_SRAM_ATTRIBUTES uint32_t puf_sram_seed;
|
|
|
|
/* Allocation of the PUF seed state */
|
|
PUF_SRAM_ATTRIBUTES uint32_t puf_sram_state;
|
|
|
|
/* Allocation of the PUF soft reset counter */
|
|
PUF_SRAM_ATTRIBUTES uint32_t puf_sram_softreset_cnt;
|
|
|
|
/* Allocation of the memory marker */
|
|
PUF_SRAM_ATTRIBUTES uint32_t puf_sram_marker;
|
|
|
|
void puf_sram_init(const uint8_t *ram, size_t len)
|
|
{
|
|
/* generates a new seed value if power cycle was detected */
|
|
if (!puf_sram_softreset()) {
|
|
puf_sram_generate(ram, len);
|
|
}
|
|
}
|
|
void puf_sram_generate(const uint8_t *ram, size_t len)
|
|
{
|
|
/* build hash from start-up pattern */
|
|
puf_sram_seed = dek_hash(ram, len);
|
|
/* write marker to a defined section for subsequent reset detection */
|
|
puf_sram_marker = PUF_SRAM_MARKER;
|
|
/* setting state to 0 means seed was generated from SRAM pattern */
|
|
puf_sram_state = 0;
|
|
/* reset counter of detected soft resets */
|
|
puf_sram_softreset_cnt = 0;
|
|
}
|
|
|
|
bool puf_sram_softreset(void)
|
|
{
|
|
if (puf_sram_marker != PUF_SRAM_MARKER) {
|
|
puf_sram_state = 2;
|
|
return 0;
|
|
}
|
|
puf_sram_state = 1;
|
|
|
|
/* increment number of detected soft resets */
|
|
puf_sram_softreset_cnt++;
|
|
|
|
/* generate alterntive seed value */
|
|
puf_sram_seed ^= puf_sram_softreset_cnt;
|
|
puf_sram_seed = dek_hash((uint8_t *)&puf_sram_seed, sizeof(puf_sram_seed));
|
|
return 1;
|
|
}
|