aes-internal.h 2.92 KB
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/* aes-internal.h
 *
 * The aes/rijndael block cipher.
 */

/* nettle, low-level cryptographics library
 *
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 * Copyright (C) 2001 Niels Möller
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 *  
 * The nettle library is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation; either version 2.1 of the License, or (at your
 * option) any later version.
 * 
 * The nettle library 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 Lesser General Public
 * License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public License
 * along with the nettle library; see the file COPYING.LIB.  If not, write to
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 * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
 * MA 02111-1301, USA.
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 */

#ifndef NETTLE_AES_INTERNAL_H_INCLUDED
#define NETTLE_AES_INTERNAL_H_INCLUDED

#include "aes.h"

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

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

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#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];
};

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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);

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

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#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))

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#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))
     
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/* Globally visible so that the same sbox table can be used by aes_set_encrypt_key */
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extern const struct aes_table _aes_encrypt_table;
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#define aes_sbox (_aes_encrypt_table.sbox)
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#endif /* NETTLE_AES_INTERNAL_H_INCLUDED */