aesdata.c

#if HAVE_CONFIG_H
# include "config.h"
#endif

#include <assert.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>

#include "nettle-types.h"

#if 1
# define BYTE_FORMAT "0x%02x"
# define BYTE_COLUMNS 8
#else
# define BYTE_FORMAT "%3d"
# define BYTE_COLUMNS 0x10
#endif

#define WORD_FORMAT "0x%08x"
#define WORD_COLUMNS 4

uint8_t sbox[0x100];
uint8_t isbox[0x100];

uint8_t gf2_log[0x100];
uint8_t gf2_exp[0x100];

uint32_t dtable[4][0x100];
uint32_t itable[4][0x100];

static unsigned
xtime(unsigned x)
{
  assert (x < 0x100);

  x <<= 1;
  if (x & 0x100)
    x ^= 0x11b;

  assert (x < 0x100);

  return x;
}

/* Computes the exponentiatiom and logarithm tables for GF_2, to the
 * base x+1 (0x03). The unit element is 1 (0x01).*/
static void
compute_log(void)
{
  unsigned i = 0;
  unsigned x = 1;

  memset(gf2_log, 0, 0x100);
  
  for (i = 0; i < 0x100; i++, x = x ^ xtime(x))
    {
      gf2_exp[i] = x;
      gf2_log[x] = i;
    }
  /* Invalid. */
  gf2_log[0] = 0;
  /* The loop above sets gf2_log[1] = 0xff, which is correct,
   * but gf2_log[1] = 0 is nicer. */
  gf2_log[1] = 0;
}

static unsigned
mult(unsigned a, unsigned b)
{