aes-internal.h

/* aes-internal.h

   The aes/rijndael block cipher.

   Copyright (C) 2001, 2013 Niels Möller

   This file is part of GNU Nettle.

   GNU Nettle is free software: you can redistribute it and/or
   modify it under the terms of either:

     * the GNU Lesser General Public License as published by the Free
       Software Foundation; either version 3 of the License, or (at your
       option) any later version.

   or

     * the GNU General Public License as published by the Free
       Software Foundation; either version 2 of the License, or (at your
       option) any later version.

   or both in parallel, as here.

   GNU Nettle is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   General Public License for more details.

   You should have received copies of the GNU General Public License and
   the GNU Lesser General Public License along with this program.  If
   not, see http://www.gnu.org/licenses/.
*/

#ifndef NETTLE_AES_INTERNAL_H_INCLUDED
#define NETTLE_AES_INTERNAL_H_INCLUDED

#include "aes.h"

/* Name mangling */
#define _aes_set_key _nettle_aes_set_key
#define _aes_invert _nettle_aes_invert
#define _aes_encrypt _nettle_aes_encrypt
#define _aes_decrypt _nettle_aes_decrypt
#define _aes_encrypt_table _nettle_aes_encrypt_table

/* Define to use only small tables. */
#ifndef AES_SMALL
# define AES_SMALL 0
#endif

#if AES_SMALL
# define AES_TABLE_SIZE 1
#else
# define AES_TABLE_SIZE 4
#endif

struct aes_table
{
  uint8_t sbox[0x100];
  uint32_t table[AES_TABLE_SIZE][0x100];
};

void
_aes_set_key(unsigned nr, unsigned nk,
	     uint32_t *subkeys, const uint8_t *key);

void
_aes_invert(unsigned rounds, uint32_t *dst, const uint32_t *src);

void
_aes_encrypt(unsigned rounds, const uint32_t *keys,
	     const struct aes_table *T,
	     size_t length, uint8_t *dst,
	     const uint8_t *src);

void
_aes_decrypt(unsigned rounds, const uint32_t *keys,
	     const struct aes_table *T,
	     size_t length, uint8_t *dst,
	     const uint8_t *src);

/* Macros */
/* Get the byte with index 0, 1, 2 and 3 */
#define B0(x) ((x) & 0xff)
#define B1(x) (((x) >> 8) & 0xff)
#define B2(x) (((x) >> 16) & 0xff)
#define B3(x) (((x) >> 24) & 0xff)

#define SUBBYTE(x, box) ((uint32_t)(box)[B0(x)]		\
		      | ((uint32_t)(box)[B1(x)] << 8)	\
		      | ((uint32_t)(box)[B2(x)] << 16)	\
		      | ((uint32_t)(box)[B3(x)] << 24))

#define AES_ROUND(T, w0, w1, w2, w3, k)		\
((  T->table[0][ B0(w0) ]			\
  ^ T->table[1][ B1(w1) ]			\
  ^ T->table[2][ B2(w2) ]			\
  ^ T->table[3][ B3(w3) ]) ^ (k))

#define AES_FINAL_ROUND(T, w0, w1, w2, w3, k)		\
((   (uint32_t) T->sbox[ B0(w0) ]			\
  | ((uint32_t) T->sbox[ B1(w1) ] << 8)			\
  | ((uint32_t) T->sbox[ B2(w2) ] << 16)		\
  | ((uint32_t) T->sbox[ B3(w3) ] << 24)) ^ (k))
     
/* Globally visible so that the same sbox table can be used by aes_set_encrypt_key */

extern const struct aes_table _aes_encrypt_table;
#define aes_sbox (_aes_encrypt_table.sbox)

#endif /* NETTLE_AES_INTERNAL_H_INCLUDED */