3 This file is part of the AVR-Crypto-Lib.
4 Copyright (C) 2008, 2009 Daniel Otte (daniel.otte@rub.de)
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.
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.
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/>.
24 #include "aes_invsbox.h"
26 #include <avr/pgmspace.h>
28 void aes_invshiftrow(void* data, uint8_t shift){
30 tmp[0] = ((uint8_t*)data)[(4+0-shift)&3];
31 tmp[1] = ((uint8_t*)data)[(4+1-shift)&3];
32 tmp[2] = ((uint8_t*)data)[(4+2-shift)&3];
33 tmp[3] = ((uint8_t*)data)[(4+3-shift)&3];
37 void aes_invshiftcol(void* data, uint8_t shift){
39 tmp[0] = ((uint8_t*)data)[ 0];
40 tmp[1] = ((uint8_t*)data)[ 4];
41 tmp[2] = ((uint8_t*)data)[ 8];
42 tmp[3] = ((uint8_t*)data)[12];
43 ((uint8_t*)data)[ 0] = tmp[(4-shift+0)&3];
44 ((uint8_t*)data)[ 4] = tmp[(4-shift+1)&3];
45 ((uint8_t*)data)[ 8] = tmp[(4-shift+2)&3];
46 ((uint8_t*)data)[12] = tmp[(4-shift+3)&3];
49 void aes_dec_round(aes_cipher_state_t* state, const aes_roundkey_t* k){
55 tmp[i] = state->s[i] ^ k->ks[i];
59 t = tmp[4*i+3] ^ tmp[4*i+2];
60 u = tmp[4*i+1] ^ tmp[4*i+0];
62 v = gf256mul(0x09, v, 0x1b);
63 w = v ^ gf256mul(0x04, tmp[4*i+2] ^ tmp[4*i+0], 0x1b);
64 v = v ^ gf256mul(0x04, tmp[4*i+3] ^ tmp[4*i+1], 0x1b);
65 state->s[4*i+3] = tmp[4*i+3] ^ v ^ gf256mul(0x02, tmp[4*i+0] ^ tmp[4*i+3], 0x1b);
66 state->s[4*i+2] = tmp[4*i+2] ^ w ^ gf256mul(0x02, t, 0x1b);
67 state->s[4*i+1] = tmp[4*i+1] ^ v ^ gf256mul(0x02, tmp[4*i+2] ^ tmp[4*i+1], 0x1b);
68 state->s[4*i+0] = tmp[4*i+0] ^ w ^ gf256mul(0x02, u, 0x1b);
72 gf256mul(0xe, tmp[4*i+0], 0x1b)
73 ^ gf256mul(0xb, tmp[4*i+1], 0x1b)
74 ^ gf256mul(0xd, tmp[4*i+2], 0x1b)
75 ^ gf256mul(0x9, tmp[4*i+3], 0x1b);
77 gf256mul(0x9, tmp[4*i+0], 0x1b)
78 ^ gf256mul(0xe, tmp[4*i+1], 0x1b)
79 ^ gf256mul(0xb, tmp[4*i+2], 0x1b)
80 ^ gf256mul(0xd, tmp[4*i+3], 0x1b);
82 gf256mul(0xd, tmp[4*i+0], 0x1b)
83 ^ gf256mul(0x9, tmp[4*i+1], 0x1b)
84 ^ gf256mul(0xe, tmp[4*i+2], 0x1b)
85 ^ gf256mul(0xb, tmp[4*i+3], 0x1b);
87 gf256mul(0xb, tmp[4*i+0], 0x1b)
88 ^ gf256mul(0xd, tmp[4*i+1], 0x1b)
89 ^ gf256mul(0x9, tmp[4*i+2], 0x1b)
90 ^ gf256mul(0xe, tmp[4*i+3], 0x1b);
94 aes_invshiftcol(state->s+1, 1);
95 aes_invshiftcol(state->s+2, 2);
96 aes_invshiftcol(state->s+3, 3);
99 state->s[i] = pgm_read_byte(aes_invsbox+state->s[i]);
105 void aes_dec_firstround(aes_cipher_state_t* state, const aes_roundkey_t* k){
109 state->s[i] ^= k->ks[i];
112 aes_invshiftcol(state->s+1, 1);
113 aes_invshiftcol(state->s+2, 2);
114 aes_invshiftcol(state->s+3, 3);
117 state->s[i] = pgm_read_byte(aes_invsbox+state->s[i]);
121 void aes_decrypt_core(aes_cipher_state_t* state, const aes_genctx_t* ks, uint8_t rounds){
123 aes_dec_firstround(state, &(ks->key[i=rounds]));
124 for(;rounds>1;--rounds){
126 aes_dec_round(state, &(ks->key[i]));
129 state->s[i] ^= ks->key[0].ks[i];