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improving bigint stuff and fixing problems for 32-bit systems
[avr-crypto-lib.git] / aes / aes_enc.c
1 /* aes_enc.c */
2 /*
3     This file is part of the AVR-Crypto-Lib.
4     Copyright (C) 2008  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 #include <avr/pgmspace.h>
35
36 void aes_shiftcol(void *data, uint8_t shift){
37         uint8_t tmp[4];
38         tmp[0] = ((uint8_t*)data)[ 0];
39         tmp[1] = ((uint8_t*)data)[ 4];
40         tmp[2] = ((uint8_t*)data)[ 8];
41         tmp[3] = ((uint8_t*)data)[12];
42         ((uint8_t*)data)[ 0] = tmp[(shift+0)&3];
43         ((uint8_t*)data)[ 4] = tmp[(shift+1)&3];
44         ((uint8_t*)data)[ 8] = tmp[(shift+2)&3];
45         ((uint8_t*)data)[12] = tmp[(shift+3)&3];
46 }
47
48 #define GF256MUL_1(a) (a)
49 #define GF256MUL_2(a) (gf256mul(2, (a), 0x1b))
50 #define GF256MUL_3(a) (gf256mul(3, (a), 0x1b))
51
52 static
53 void aes_enc_round(aes_cipher_state_t *state, const aes_roundkey_t *k){
54         uint8_t tmp[16], t;
55         uint8_t i;
56         /* subBytes */
57         for(i=0; i<16; ++i){
58                 tmp[i] = pgm_read_byte(aes_sbox+state->s[i]);
59         }
60         /* shiftRows */
61         aes_shiftcol(tmp+1, 1);
62         aes_shiftcol(tmp+2, 2);
63         aes_shiftcol(tmp+3, 3);
64         /* mixColums */
65         for(i=0; i<4; ++i){
66                 t = tmp[4*i+0] ^ tmp[4*i+1] ^ tmp[4*i+2] ^ tmp[4*i+3];
67                 state->s[4*i+0] =
68                           GF256MUL_2(tmp[4*i+0]^tmp[4*i+1])
69                         ^ tmp[4*i+0]
70                         ^ t;
71                 state->s[4*i+1] =
72                           GF256MUL_2(tmp[4*i+1]^tmp[4*i+2])
73                         ^ tmp[4*i+1]
74                         ^ t;
75                 state->s[4*i+2] =
76                           GF256MUL_2(tmp[4*i+2]^tmp[4*i+3])
77                         ^ tmp[4*i+2]
78                         ^ t;
79                 state->s[4*i+3] =
80                           GF256MUL_2(tmp[4*i+3]^tmp[4*i+0])
81                         ^ tmp[4*i+3]
82                         ^ t;
83         }
84
85         /* addKey */
86         for(i=0; i<16; ++i){
87                 state->s[i] ^= k->ks[i];
88         }
89 }
90
91
92 static
93 void aes_enc_lastround(aes_cipher_state_t *state,const aes_roundkey_t *k){
94         uint8_t i;
95         /* subBytes */
96         for(i=0; i<16; ++i){
97                 state->s[i] = pgm_read_byte(aes_sbox+state->s[i]);
98         }
99         /* shiftRows */
100         aes_shiftcol(state->s+1, 1);
101         aes_shiftcol(state->s+2, 2);
102         aes_shiftcol(state->s+3, 3);
103         /* keyAdd */
104         for(i=0; i<16; ++i){
105                 state->s[i] ^= k->ks[i];
106         }
107 }
108
109 void aes_encrypt_core(aes_cipher_state_t *state, const aes_genctx_t *ks, uint8_t rounds){
110         uint8_t i;
111         for(i=0; i<16; ++i){
112                 state->s[i] ^= ks->key[0].ks[i];
113         }
114         i=1;
115         for(;rounds>1;--rounds){
116                 aes_enc_round(state, &(ks->key[i]));
117                 ++i;
118         }
119         aes_enc_lastround(state, &(ks->key[i]));
120 }