124 lines
3.0 KiB
C
124 lines
3.0 KiB
C
/* aes_enc.c */
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/*
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This file is part of the Crypto-avr-lib/microcrypt-lib.
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Copyright (C) 2008 Daniel Otte (daniel.otte@rub.de)
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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 daniel.otte@rub.de
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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_shiftrow(void* data, uint8_t shift){
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uint8_t tmp[4];
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tmp[0] = ((uint8_t*)data)[(0+shift)&3];
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tmp[1] = ((uint8_t*)data)[(1+shift)&3];
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tmp[2] = ((uint8_t*)data)[(2+shift)&3];
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tmp[3] = ((uint8_t*)data)[(3+shift)&3];
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memcpy(data, tmp, 4);
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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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uint8_t tmp[16];
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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_shiftrow(tmp+4, 1);
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aes_shiftrow(tmp+8, 2);
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aes_shiftrow(tmp+12, 3);
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/* mixColums */
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for(i=0; i<4; ++i){
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state->s[4*0+i] =
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GF256MUL_2(tmp[4*0+i])
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^ GF256MUL_3(tmp[4*1+i])
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^ GF256MUL_1(tmp[4*2+i])
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^ GF256MUL_1(tmp[4*3+i]);
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state->s[4*1+i] =
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GF256MUL_1(tmp[4*0+i])
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^ GF256MUL_2(tmp[4*1+i])
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^ GF256MUL_3(tmp[4*2+i])
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^ GF256MUL_1(tmp[4*3+i]);
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state->s[4*2+i] =
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GF256MUL_1(tmp[4*0+i])
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^ GF256MUL_1(tmp[4*1+i])
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^ GF256MUL_2(tmp[4*2+i])
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^ GF256MUL_3(tmp[4*3+i]);
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state->s[4*3+i] =
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GF256MUL_3(tmp[4*0+i])
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^ GF256MUL_1(tmp[4*1+i])
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^ GF256MUL_1(tmp[4*2+i])
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^ GF256MUL_2(tmp[4*3+i]);
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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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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_shiftrow(state->s+4, 1);
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aes_shiftrow(state->s+8, 2);
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aes_shiftrow(state->s+12, 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, uint8_t rounds){
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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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