95 lines
2.7 KiB
C
95 lines
2.7 KiB
C
/* aes_keyschedule.c */
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/*
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This file is part of the AVR-Crypto-Lib.
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Copyright (C) 2008, 2009 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_keyschedule.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 "aes.h"
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#include "aes_keyschedule.h"
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#include "aes_sbox.h"
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#include <string.h>
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#include <avr/pgmspace.h>
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static
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void aes_rotword(void* a){
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uint8_t t;
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t=((uint8_t*)a)[0];
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((uint8_t*)a)[0] = ((uint8_t*)a)[1];
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((uint8_t*)a)[1] = ((uint8_t*)a)[2];
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((uint8_t*)a)[2] = ((uint8_t*)a)[3];
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((uint8_t*)a)[3] = t;
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}
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const uint8_t rc_tab[] PROGMEM = { 0x01, 0x02, 0x04, 0x08,
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0x10, 0x20, 0x40, 0x80,
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0x1b, 0x36 };
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void aes_init(const void* key, uint16_t keysize_b, aes_genctx_t* ctx){
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uint8_t hi,i,nk, next_nk;
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uint8_t rc=0;
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union {
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uint32_t v32;
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uint8_t v8[4];
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} tmp;
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nk=keysize_b>>5; /* 4, 6, 8 */
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hi=4*(nk+6+1);
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memcpy(ctx, key, keysize_b/8);
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next_nk = nk;
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for(i=nk;i<hi;++i){
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tmp.v32 = ((uint32_t*)(ctx->key[0].ks))[i-1];
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if(i!=next_nk){
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if(nk==8 && i%8==4){
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tmp.v8[0] = pgm_read_byte(aes_sbox+tmp.v8[0]);
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tmp.v8[1] = pgm_read_byte(aes_sbox+tmp.v8[1]);
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tmp.v8[2] = pgm_read_byte(aes_sbox+tmp.v8[2]);
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tmp.v8[3] = pgm_read_byte(aes_sbox+tmp.v8[3]);
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}
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} else {
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next_nk += nk;
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aes_rotword(&(tmp.v32));
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tmp.v8[0] = pgm_read_byte(aes_sbox+tmp.v8[0]);
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tmp.v8[1] = pgm_read_byte(aes_sbox+tmp.v8[1]);
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tmp.v8[2] = pgm_read_byte(aes_sbox+tmp.v8[2]);
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tmp.v8[3] = pgm_read_byte(aes_sbox+tmp.v8[3]);
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tmp.v8[0] ^= pgm_read_byte(rc_tab+rc);
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rc++;
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}
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((uint32_t*)(ctx->key[0].ks))[i] = ((uint32_t*)(ctx->key[0].ks))[i-nk]
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^ tmp.v32;
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}
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}
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void aes128_init(const void* key, aes128_ctx_t* ctx){
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aes_init(key, 128, (aes_genctx_t*)ctx);
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}
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void aes192_init(const void* key, aes192_ctx_t* ctx){
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aes_init(key, 192, (aes_genctx_t*)ctx);
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}
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void aes256_init(const void* key, aes256_ctx_t* ctx){
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aes_init(key, 256, (aes_genctx_t*)ctx);
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}
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