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[avr-crypto-lib.git] / shabea / shabea.c

diff --git a/shabea/shabea.c b/shabea/shabea.c
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+/* shabea.c */
+/*
+ *   This file is part of AnonAccess, an access system which can be used
+ *    to open door or doing other things with an anonymity featured
+ *    account managment.
+ *   Copyright (C) 2006, 2007, 2008  Daniel Otte (daniel.otte@rub.de)
+ *
+ *   This program is free software: you can redistribute it and/or modify
+ *   it under the terms of the GNU General Public License as published by
+ *   the Free Software Foundation, either version 3 of the License, or
+ *   (at your option) any later version.
+ *
+ *   This program is distributed in the hope that it will be useful,
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *   GNU General Public License for more details.
+ *
+ *   You should have received a copy of the GNU General Public License
+ *   along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/**
+ * \file       shabea.c
+ * \author     Daniel Otte 
+ * \date       2007-06-07
+ * \brief      SHABEA - a SHA Based Encryption Algorithm implementation
+ * \par License        
+ * GPL
+ * 
+ * SHABEAn-r where n is the blocksize and r the number of round used
+ * 
+ * 
+ */
+#include <stdlib.h>
+#include <string.h>
+#include "sha256.h"
+
+#include "config.h"
+#include "memxor.h"
+
+
+/*
+ * SHABEA256-n
+ */ 
+ 
+#define SHABEA_BLOCKSIZE 256
+#define SHABEA_BLOCKSIZEB (SHABEA_BLOCKSIZE/8)
+#define SHABEA_HALFSIZEB  (SHABEA_BLOCKSIZEB/2)
+#define SHABEA_HALFSIZE (SHABEA_BLOCKSIZE/2)
+
+#define L ((uint8_t*)block+ 0)
+#define R ((uint8_t*)block+16)
+void shabea256(void * block, void * key, uint16_t keysize_b, uint8_t enc, uint8_t rounds){
+       uint8_t r;              /**/
+       uint8_t tb[SHABEA_HALFSIZEB+2+(keysize_b+7)/8]; /**/
+       uint16_t kbs;   /* bytes used for the key / temporary block */
+       sha256_hash_t hash;
+       uint8_t termcond; 
+       int8_t dir;
+       if(enc){
+               r = 0;
+               termcond = rounds-1;
+               dir = 1;
+       } else {
+               r = rounds-1;
+               termcond = 0;
+               dir = -1;
+       }
+       kbs = (keysize_b+7)/8;
+       memcpy(tb+SHABEA_HALFSIZEB+2, key, kbs); /* copy key to temporary block */
+       tb[SHABEA_HALFSIZEB+0] = 0;     /* set round counter high value to zero */
+       
+       for(;;r+=dir){ /* enc: 0..(rounds-1) ; !enc: (rounds-1)..0 */
+               memcpy(tb, R, SHABEA_HALFSIZEB); /* copy right half into tb */
+               tb[SHABEA_HALFSIZEB+1] = r;
+               sha256(&hash, tb, SHABEA_HALFSIZE+16+keysize_b);
+               if(r!=termcond){        
+                       /* swap */
+                       memxor(hash, L, SHABEA_HALFSIZEB);
+                       memcpy(L, R, SHABEA_HALFSIZEB);
+                       memcpy(R, hash, SHABEA_HALFSIZEB);
+               } else {
+                       /* last round */
+                       /* no swap */
+                       memxor(L, hash, SHABEA_HALFSIZEB);
+                       return; 
+               }
+       }
+}
+
+