aes/aes_enc.c

   1 /* aes_enc.c */
   2 /*
   3     This file is part of the ARM-Crypto-Lib.
   4     Copyright (C) 2006-2010  Daniel Otte (daniel.otte@rub.de)
   5
   6     This program is free software: you can redistribute it and/or modify
   7     it under the terms of the GNU General Public License as published by
   8     the Free Software Foundation, either version 3 of the License, or
   9     (at your option) any later version.
  10
  11     This program is distributed in the hope that it will be useful,
  12     but WITHOUT ANY WARRANTY; without even the implied warranty of
  13     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14     GNU General Public License for more details.
  15
  16     You should have received a copy of the GNU General Public License
  17     along with this program.  If not, see <http://www.gnu.org/licenses/>.
  18 */
  19 /**
  20  * \file     aes_enc.c
  21  * \email    daniel.otte@rub.de
  22  * \author   Daniel Otte
  23  * \date     2008-12-30
  24  * \license  GPLv3 or later
  25  *
  26  */
  27
  28 #include <stdint.h>
  29 #include <string.h>
  30 #include "aes.h"
  31 #include "gf256mul.h"
  32 #include "aes_sbox.h"
  33 #include "aes_enc.h"
  34
  35 void aes_shiftcol(void* data, uint8_t shift){
  36         uint8_t tmp[4];
  37         tmp[0] = ((uint8_t*)data)[ 0];
  38         tmp[1] = ((uint8_t*)data)[ 4];
  39         tmp[2] = ((uint8_t*)data)[ 8];
  40         tmp[3] = ((uint8_t*)data)[12];
  41         ((uint8_t*)data)[ 0] = tmp[(shift+0)&3];
  42         ((uint8_t*)data)[ 4] = tmp[(shift+1)&3];
  43         ((uint8_t*)data)[ 8] = tmp[(shift+2)&3];
  44         ((uint8_t*)data)[12] = tmp[(shift+3)&3];
  45 }
  46
  47 #define GF256MUL_1(a) (a)
  48 #define GF256MUL_2(a) (gf256mul(2, (a), 0x1b))
  49 #define GF256MUL_3(a) (gf256mul(3, (a), 0x1b))
  50
  51 static
  52 void aes_enc_round(aes_cipher_state_t* state, const aes_roundkey_t* k){
  53         uint8_t tmp[16], t;
  54         uint8_t i;
  55         /* subBytes */
  56         for(i=0; i<16; ++i){
  57                 tmp[i] = aes_sbox[state->s[i]];
  58         }
  59         /* shiftRows */
  60         aes_shiftcol(tmp+1, 1);
  61         aes_shiftcol(tmp+2, 2);
  62         aes_shiftcol(tmp+3, 3);
  63         /* mixColums */
  64         for(i=0; i<4; ++i){
  65                 t = tmp[4*i+0] ^ tmp[4*i+1] ^ tmp[4*i+2] ^ tmp[4*i+3];
  66                 state->s[4*i+0] =
  67                           GF256MUL_2(tmp[4*i+0]^tmp[4*i+1])
  68                         ^ tmp[4*i+0]
  69                         ^ t;
  70                 state->s[4*i+1] =
  71                           GF256MUL_2(tmp[4*i+1]^tmp[4*i+2])
  72                         ^ tmp[4*i+1]
  73                         ^ t;
  74                 state->s[4*i+2] =
  75                           GF256MUL_2(tmp[4*i+2]^tmp[4*i+3])
  76                         ^ tmp[4*i+2]
  77                         ^ t;
  78                 state->s[4*i+3] =
  79                           GF256MUL_2(tmp[4*i+3]^tmp[4*i+0])
  80                         ^ tmp[4*i+3]
  81                         ^ t;
  82         }
  83
  84         /* addKey */
  85         for(i=0; i<16; ++i){
  86                 state->s[i] ^= k->ks[i];
  87         }
  88 }
  89
  90
  91 static
  92 void aes_enc_lastround(aes_cipher_state_t* state,const aes_roundkey_t* k){
  93         uint8_t i;
  94         /* subBytes */
  95         for(i=0; i<16; ++i){
  96                 state->s[i] = aes_sbox[state->s[i]];
  97         }
  98         /* shiftRows */
  99         aes_shiftcol(state->s+1, 1);
 100         aes_shiftcol(state->s+2, 2);
 101         aes_shiftcol(state->s+3, 3);
 102         /* keyAdd */
 103         for(i=0; i<16; ++i){
 104                 state->s[i] ^= k->ks[i];
 105         }
 106 }
 107
 108 void aes_encrypt_core(aes_cipher_state_t* state, const aes_genctx_t* ks, uint8_t rounds){
 109         uint8_t i;
 110         for(i=0; i<16; ++i){
 111                 state->s[i] ^= ks->key[0].ks[i];
 112         }
 113         i=1;
 114         for(;rounds>1;--rounds){
 115                 aes_enc_round(state, &(ks->key[i]));
 116                 ++i;
 117         }
 118         aes_enc_lastround(state, &(ks->key[i]));
 119 }