shabea.c

   1 /**
   2  * \file        shabea.c
   3  * \author      Daniel Otte
   4  * \date        2007-06-07
   5  * \brief       SHABEA - a SHA Based Encrytion Algorithm implementation
   6  * \par License
   7  * GPL
   8  *
   9  * SHABEAn-r where n is the blocksize and r the number of round used
  10  *
  11  *
  12  */
  13 #include <stdlib.h>
  14 #include <string.h>
  15 #include "sha256.h"
  16
  17 #include "config.h"
  18 #include "uart.h"
  19 #include "debug.h"
  20 /*
  21  *
  22  */
  23 static
  24 void memxor(uint8_t * dest, uint8_t * src, uint8_t length){
  25         while(length--){
  26                 *dest++ ^= *src++;
  27         }
  28 }
  29
  30 /*
  31  * SHABEA128-16
  32  */
  33 #define L ((uint8_t*)block+0)
  34 #define R ((uint8_t*)block+8)
  35 void shabea128(void * block, void * key, uint16_t keysize, uint8_t enc, uint8_t rounds){
  36         int8_t r;               /**/
  37         uint8_t *tb;    /**/
  38         uint16_t kbs;   /* bytes used for the key / temporary block */
  39         sha256_hash_t hash;
  40
  41         r = (enc?0:(rounds-1));
  42         kbs = keysize/8 + ((keysize&7)?1:0);
  43         tb = malloc(8+2+kbs);
  44         memcpy(tb+8+2, key, kbs);
  45         tb[8+0] = 0;
  46
  47         for(;r!=(enc?(rounds):-1);enc?r++:r--){ /* enc: 0..(rounds-1) ; !enc: (rounds-1)..0 */
  48                 memcpy(tb, R, 8); /* copy right half into tb */
  49                 tb[8+1] = r;
  50                 sha256(hash, tb, 64+16+keysize);
  51                 if(!(r==(enc?(rounds-1):0))){
  52                         /* swap */
  53                         memxor(hash, L, 8);
  54                         memcpy(L, R, 8);
  55                         memcpy(R, hash, 8);
  56                 } else {
  57                         /* no swap */
  58                         memxor(L, hash, 8);
  59                 }
  60         }
  61         free(tb);
  62 }
  63
  64