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/* aes.c
*
* The aes/rijndael block cipher.
*/
/* nettle, low-level cryptographics library
*
* Copyright (C) 2000, 2001 Rafael R. Sevilla, Niels Mller
*
* 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
* the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
* MA 02111-1307, USA.
*/
/* Originally written by Rafael R. Sevilla <dido@pacific.net.ph> */
#if HAVE_CONFIG_H
# include "config.h"
#endif
#include <assert.h>
#include "aes-internal.h"
#include "macros.h"
#ifndef AES_DEBUG
# define AES_DEBUG 0
#endif
#if AES_DEBUG
# include <stdio.h>
static void
d4(const char *name, unsigned r, const uint32_t *data)
{
unsigned j;
fprintf(stderr, "aes, %d, %s: ", r, name);
for (j = 0; j<4; j++)
fprintf(stderr, "%08x, ", data[j]);
fprintf(stderr, "\n");
}
static void
d2(const char *aname, uint32_t a, const char *bname, uint32_t b)
{
fprintf(stderr, "aes, %s: %08x, %s, %08x\n",
aname, a, bname, b);
}
static void
d1(const char *name, uint32_t a)
{
fprintf(stderr, "aes, %s: %08x\n",
name, a);
}
# define D4(x) d4 x
# define D2(x) d2 x
# define D1(x) d2 x
#else
# define D4(x)
# define D2(x)
# define D1(x)
#endif
/* 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 IDX0(j) (j)
#define IDX1(j) (T->idx[0][j])
#define IDX2(j) (T->idx[1][j])
#define IDX3(j) (T->idx[2][j])
/* NOTE: IDX2 can be done as j ^ 2, but that doesn't seem to make much
* of a difference. */
#define SWAP(a, b) \
do { uint32_t *t_swap = (a); (a) = (b); (b) = t_swap; } while(0)
void
_aes_crypt(const struct aes_ctx *ctx,
const struct aes_table *T,
unsigned length, uint8_t *dst,
const uint8_t *src)
{
FOR_BLOCKS(length, dst, src, AES_BLOCK_SIZE)
{
/* Use double buffering, reading one half of the buffer writing
* to the other, and then swapping the role of the two
* halves. */
uint32_t buffer[8];
uint32_t *wtxt; /* working ciphertext */
uint32_t *tmp;
unsigned i;
unsigned round;
wtxt = buffer; tmp = buffer + 4;
/* Get clear text, using little-endian byte order.
* Also XOR with the first subkey. */
for (i = 0; i<4; i++)
wtxt[i] = LE_READ_UINT32(src + 4*i) ^ ctx->keys[i];
for (round = 1; round < ctx->nrounds; round++)
{
unsigned j;
D4(("wtxt", round, wtxt));
D4(("key", round, &ctx->keys[4*round]));
/* What's the best way to order this loop? Ideally,
* we'd want to keep both t and wtxt in registers. */
for (j=0; j<4; j++)
{
/* FIXME: Figure out how the indexing should really be
* done. With the current idx arrays, it looks like the
* code shifts the rows in the wrong direction. But it
* passes the testsuite. Perhaps the tables are rotated
* in the wrong direction, but I don't think so. */
uint32_t t;
#if AES_SMALL
t = T->table[0][ B0(wtxt[IDX0(j)]) ] ^
ROTRBYTE( T->table[0][ B1(wtxt[IDX1(j)]) ]^
ROTRBYTE( T->table[0][ B2(wtxt[IDX2(j)]) ] ^
ROTRBYTE(T->table[0][ B3(wtxt[IDX3(j)]) ])));
#else /* !AES_SMALL */
t = ( T->table[0][ B0(wtxt[IDX0(j)]) ]
^ T->table[1][ B1(wtxt[IDX1(j)]) ]
^ T->table[2][ B2(wtxt[IDX2(j)]) ]
^ T->table[3][ B3(wtxt[IDX3(j)]) ]);
#endif /* !AES_SMALL */
D1(("t", t));
tmp[j] = t ^ ctx->keys[4*round + j];
}
SWAP(tmp, wtxt);
#if 0
D4(("t", round, t));
for (j = 0; j<4; j++)
wtxt[j] = t[j] ^ ctx->keys[4*round + j];
#endif
}
/* Final round */
{
uint32_t out;
unsigned j;
for (j = 0; j<4; j++)
{
/* FIXME: Figure out how the indexing should really be done.
* It looks like this code shifts the rows in the wrong
* direction, but it passes the testsuite. */
out = ( (uint32_t) T->sbox[ B0(wtxt[IDX0(j)]) ]
| ((uint32_t) T->sbox[ B1(wtxt[IDX1(j)]) ] << 8)
| ((uint32_t) T->sbox[ B2(wtxt[IDX2(j)]) ] << 16)
| ((uint32_t) T->sbox[ B3(wtxt[IDX3(j)]) ] << 24));
D2(("t", out, "key", ctx->keys[4*round + j]));
out ^= ctx->keys[4*round + j];
LE_WRITE_UINT32(dst + 4*j, out);
}
}
}
}