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56 lines
1.4 KiB
C
56 lines
1.4 KiB
C
/*
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* Copyright (C) 2018 HAW Hamburg
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*
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* This file is subject to the terms and conditions of the GNU Lesser
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* General Public License v2.1. See the file LICENSE in the top level
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* directory for more details.
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*/
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/**
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* @ingroup sys_puf_sram
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*
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* @{
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* @file
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*
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* @author Peter Kietzmann <peter.kietzmann@haw-hamburg.de>
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*
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* @}
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*/
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#include "puf_sram.h"
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/* Allocation of the PUF seed variable */
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__attribute__((used,section(".puf"))) uint32_t puf_sram_seed;
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/* Allocation of the PUF seed state */
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__attribute__((used,section(".puf"))) uint32_t puf_sram_state;
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/* Allocation of the memory marker */
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__attribute__((used,section(".puf"))) uint32_t puf_sram_marker;
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void puf_sram_init(const uint8_t *ram, size_t len)
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{
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/* generates a new seed value if power cycle was detected */
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if (!puf_sram_softreset()) {
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puf_sram_generate(ram, len);
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}
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}
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void puf_sram_generate(const uint8_t *ram, size_t len)
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{
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/* build hash from start-up pattern */
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puf_sram_seed = dek_hash(ram, len);
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/* write marker to a defined section for subsequent reset detection */
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puf_sram_marker = PUF_SRAM_MARKER;
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/* seting state to 0 means seed was generated from SRAM pattern */
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puf_sram_state = 0;
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}
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bool puf_sram_softreset(void)
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{
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if (puf_sram_marker != PUF_SRAM_MARKER) {
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puf_sram_state = 2;
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return 0;
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}
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puf_sram_state = 1;
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return 1;
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}
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