92 lines
2.5 KiB
C
92 lines
2.5 KiB
C
/* shabea.c */
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/*
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* This file is part of AnonAccess, an access system which can be used
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* to open door or doing other things with an anonymity featured
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* account managment.
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* Copyright (C) 2006, 2007, 2008 Daniel Otte (daniel.otte@rub.de)
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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 3 of the License, or
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* (at your option) any later version.
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*
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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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*
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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 shabea.c
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* \author Daniel Otte
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* \date 2007-06-07
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* \brief SHABEA - a SHA Based Encryption Algorithm implementation
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* \par License
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* GPL
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*
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* SHABEAn-r where n is the blocksize and r the number of round used
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*
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*
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*/
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#include <stdlib.h>
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#include <string.h>
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#include "sha256.h"
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#include "config.h"
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#include "memxor.h"
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/*
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* SHABEA256-n
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*/
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#define SHABEA_BLOCKSIZE 256
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#define SHABEA_BLOCKSIZEB (SHABEA_BLOCKSIZE/8)
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#define SHABEA_HALFSIZEB (SHABEA_BLOCKSIZEB/2)
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#define SHABEA_HALFSIZE (SHABEA_BLOCKSIZE/2)
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#define L ((uint8_t*)block+ 0)
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#define R ((uint8_t*)block+16)
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void shabea256(void * block, void * key, uint16_t keysize_b, uint8_t enc, uint8_t rounds){
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uint8_t r; /**/
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uint8_t tb[SHABEA_HALFSIZEB+2+(keysize_b+7)/8]; /**/
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uint16_t kbs; /* bytes used for the key / temporary block */
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sha256_hash_t hash;
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uint8_t termcond;
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int8_t dir;
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if(enc){
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r = 0;
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termcond = rounds-1;
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dir = 1;
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} else {
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r = rounds-1;
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termcond = 0;
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dir = -1;
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}
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kbs = (keysize_b+7)/8;
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memcpy(tb+SHABEA_HALFSIZEB+2, key, kbs); /* copy key to temporary block */
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tb[SHABEA_HALFSIZEB+0] = 0; /* set round counter high value to zero */
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for(;;r+=dir){ /* enc: 0..(rounds-1) ; !enc: (rounds-1)..0 */
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memcpy(tb, R, SHABEA_HALFSIZEB); /* copy right half into tb */
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tb[SHABEA_HALFSIZEB+1] = r;
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sha256(&hash, tb, SHABEA_HALFSIZE+16+keysize_b);
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if(r!=termcond){
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/* swap */
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memxor(hash, L, SHABEA_HALFSIZEB);
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memcpy(L, R, SHABEA_HALFSIZEB);
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memcpy(R, hash, SHABEA_HALFSIZEB);
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} else {
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/* last round */
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/* no swap */
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memxor(L, hash, SHABEA_HALFSIZEB);
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return;
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}
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}
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}
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