125 lines
3.3 KiB
C
125 lines
3.3 KiB
C
/* aes_enc.c */
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/*
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This file is part of the AVR-Crypto-Lib.
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Copyright (C) 2006-2015 Daniel Otte (bg@nerilex.org)
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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/**
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* \file aes_enc.c
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* \email bg@nerilex.org
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* \author Daniel Otte
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* \date 2008-12-30
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* \license GPLv3 or later
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*
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*/
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#include <stdint.h>
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#include <string.h>
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#include "aes.h"
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#include "gf256mul.h"
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#include "aes_sbox.h"
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#include "aes_enc.h"
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#include <avr/pgmspace.h>
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void aes_shiftcol(void *data, uint8_t shift)
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{
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uint8_t tmp[4];
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tmp[0] = ((uint8_t*) data)[0];
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tmp[1] = ((uint8_t*) data)[4];
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tmp[2] = ((uint8_t*) data)[8];
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tmp[3] = ((uint8_t*) data)[12];
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((uint8_t*) data)[0] = tmp[(shift + 0) & 3];
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((uint8_t*) data)[4] = tmp[(shift + 1) & 3];
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((uint8_t*) data)[8] = tmp[(shift + 2) & 3];
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((uint8_t*) data)[12] = tmp[(shift + 3) & 3];
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}
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#define GF256MUL_1(a) (a)
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#define GF256MUL_2(a) (gf256mul(2, (a), 0x1b))
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#define GF256MUL_3(a) (gf256mul(3, (a), 0x1b))
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static
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void aes_enc_round(aes_cipher_state_t *state, const aes_roundkey_t *k)
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{
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uint8_t tmp[16], t;
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uint8_t i;
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/* subBytes */
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for (i = 0; i < 16; ++i) {
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tmp[i] = pgm_read_byte(aes_sbox + state->s[i]);
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}
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/* shiftRows */
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aes_shiftcol(tmp + 1, 1);
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aes_shiftcol(tmp + 2, 2);
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aes_shiftcol(tmp + 3, 3);
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/* mixColums */
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for (i = 0; i < 4; ++i) {
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t = tmp[4 * i + 0] ^ tmp[4 * i + 1] ^ tmp[4 * i + 2] ^ tmp[4 * i + 3];
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state->s[4 * i + 0] =
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GF256MUL_2(tmp[4*i+0]^tmp[4*i+1])
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^ tmp[4 * i + 0]
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^ t;
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state->s[4 * i + 1] =
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GF256MUL_2(tmp[4*i+1]^tmp[4*i+2])
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^ tmp[4 * i + 1]
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^ t;
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state->s[4 * i + 2] =
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GF256MUL_2(tmp[4*i+2]^tmp[4*i+3])
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^ tmp[4 * i + 2]
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^ t;
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state->s[4 * i + 3] =
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GF256MUL_2(tmp[4*i+3]^tmp[4*i+0])
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^ tmp[4 * i + 3]
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^ t;
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}
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/* addKey */
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for (i = 0; i < 16; ++i) {
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state->s[i] ^= k->ks[i];
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}
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}
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static
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void aes_enc_lastround(aes_cipher_state_t *state, const aes_roundkey_t *k)
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{
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uint8_t i;
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/* subBytes */
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for (i = 0; i < 16; ++i) {
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state->s[i] = pgm_read_byte(aes_sbox + state->s[i]);
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}
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/* shiftRows */
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aes_shiftcol(state->s + 1, 1);
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aes_shiftcol(state->s + 2, 2);
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aes_shiftcol(state->s + 3, 3);
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/* keyAdd */
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for (i = 0; i < 16; ++i) {
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state->s[i] ^= k->ks[i];
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}
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}
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void aes_encrypt_core(aes_cipher_state_t *state, const aes_genctx_t *ks,
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uint8_t rounds)
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{
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uint8_t i;
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for (i = 0; i < 16; ++i) {
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state->s[i] ^= ks->key[0].ks[i];
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}
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i = 1;
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for (; rounds > 1; --rounds) {
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aes_enc_round(state, &(ks->key[i]));
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++i;
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}
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aes_enc_lastround(state, &(ks->key[i]));
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}
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