53 lines
1.8 KiB
C
53 lines
1.8 KiB
C
/* xtea.c */
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/*
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This file is part of the AVR-Crypto-Lib.
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Copyright (C) 2008 Daniel Otte (daniel.otte@rub.de)
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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 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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/**
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* \file xtea.c
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* \brief XTEA implemantation
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* copy'n'pasted from http://en.wikipedia.org/wiki/XTEA
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* and slightly modified
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*/
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#include <stdint.h>
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void xtea_enc(void *dest, const void *v, const void *k) {
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uint8_t i;
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uint32_t v0=((uint32_t*)v)[0], v1=((uint32_t*)v)[1];
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uint32_t sum=0, delta=0x9E3779B9;
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for(i=0; i<32; i++) {
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v0 += ((v1 << 4 ^ v1 >> 5) + v1) ^ (sum + ((uint32_t*)k)[sum & 3]);
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sum += delta;
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v1 += ((v0 << 4 ^ v0 >> 5) + v0) ^ (sum + ((uint32_t*)k)[sum>>11 & 3]);
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}
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((uint32_t*)dest)[0]=v0; ((uint32_t*)dest)[1]=v1;
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}
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void xtea_dec(void *dest, const void *v, const void *k) {
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uint8_t i;
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uint32_t v0=((uint32_t*)v)[0], v1=((uint32_t*)v)[1];
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uint32_t sum=0xC6EF3720, delta=0x9E3779B9;
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for(i=0; i<32; i++) {
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v1 -= ((v0 << 4 ^ v0 >> 5) + v0) ^ (sum + ((uint32_t*)k)[sum>>11 & 3]);
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sum -= delta;
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v0 -= ((v1 << 4 ^ v1 >> 5) + v1) ^ (sum + ((uint32_t*)k)[sum & 3]);
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}
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((uint32_t*)dest)[0]=v0; ((uint32_t*)dest)[1]=v1;
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}
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