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79 lines
1.2 KiB
C
79 lines
1.2 KiB
C
/*
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* fw/hash.h - Secure hash
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*
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* Written 2012 by Werner Almesberger
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* Copyright 2012 Werner Almesberger
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*/
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#include <stdbool.h>
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#include <stdint.h>
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#include <string.h>
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#ifdef __AVR__
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#include <avr/pgmspace.h>
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#endif /* __AVR__ */
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#include "hash.h"
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#define HASH_SIZE 128
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static uint8_t hash[HASH_SIZE];
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void hash_init(void)
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{
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memset(hash, 0, HASH_SIZE);
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}
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void hash_merge(const uint8_t *buf, uint8_t len)
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{
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uint8_t i;
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for (i = 0; i != len; i++)
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hash[i & (HASH_SIZE-1)] ^= buf[i];
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}
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#ifdef __AVR__
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void hash_merge_progmem(const uint8_t *buf, uint8_t len)
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{
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uint8_t i;
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for (i = 0; i != len; i++)
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hash[i & (HASH_SIZE-1)] ^= pgm_read_byte(buf+i);
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}
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#endif /* __AVR__ */
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void hash_end(void)
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{
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}
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bool hash_eq(const uint8_t *buf, uint8_t len, uint8_t off)
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{
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uint8_t i;
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for (i = 0; i != len; i++)
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if (hash[(off+i) & (HASH_SIZE-1)] != buf[i])
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return 0;
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return 1;
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}
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void hash_cp(uint8_t *buf, uint8_t len, uint8_t off)
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{
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memcpy(buf, hash+off, len);
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}
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