1 /* aes_keyschedule.c */
3 This file is part of the AVR-Crypto-Lib.
4 Copyright (C) 2006-2015 Daniel Otte (bg@nerilex.org)
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/>.
20 * \file aes_keyschedule.c
21 * \email bg@nerilex.org
24 * \license GPLv3 or later
30 #include "aes_keyschedule.h"
33 #include <avr/pgmspace.h>
36 void aes_rotword(void *a)
39 t = ((uint8_t*) a)[0];
40 ((uint8_t*) a)[0] = ((uint8_t*) a)[1];
41 ((uint8_t*) a)[1] = ((uint8_t*) a)[2];
42 ((uint8_t*) a)[2] = ((uint8_t*) a)[3];
43 ((uint8_t*) a)[3] = t;
46 const uint8_t rc_tab[] PROGMEM = { 0x01, 0x02, 0x04, 0x08,
47 0x10, 0x20, 0x40, 0x80,
50 void aes_init(const void *key, uint16_t keysize_b, aes_genctx_t *ctx)
52 uint8_t hi, i, nk, next_nk;
58 nk = keysize_b >> 5; /* 4, 6, 8 */
59 hi = 4 * (nk + 6 + 1);
60 memcpy(ctx, key, keysize_b / 8);
62 for (i = nk; i < hi; ++i) {
63 tmp.v32 = ((uint32_t*) (ctx->key[0].ks))[i - 1];
65 if (nk == 8 && i % 8 == 4) {
66 tmp.v8[0] = pgm_read_byte(aes_sbox + tmp.v8[0]);
67 tmp.v8[1] = pgm_read_byte(aes_sbox + tmp.v8[1]);
68 tmp.v8[2] = pgm_read_byte(aes_sbox + tmp.v8[2]);
69 tmp.v8[3] = pgm_read_byte(aes_sbox + tmp.v8[3]);
73 aes_rotword(&(tmp.v32));
74 tmp.v8[0] = pgm_read_byte(aes_sbox + tmp.v8[0]);
75 tmp.v8[1] = pgm_read_byte(aes_sbox + tmp.v8[1]);
76 tmp.v8[2] = pgm_read_byte(aes_sbox + tmp.v8[2]);
77 tmp.v8[3] = pgm_read_byte(aes_sbox + tmp.v8[3]);
78 tmp.v8[0] ^= pgm_read_byte(rc_tab + rc);
81 ((uint32_t*) (ctx->key[0].ks))[i] = ((uint32_t*) (ctx->key[0].ks))[i
87 void aes128_init(const void *key, aes128_ctx_t *ctx)
89 aes_init(key, 128, (aes_genctx_t*) ctx);
92 void aes192_init(const void *key, aes192_ctx_t *ctx)
94 aes_init(key, 192, (aes_genctx_t*) ctx);
97 void aes256_init(const void *key, aes256_ctx_t *ctx)
99 aes_init(key, 256, (aes_genctx_t*) ctx);