aes-invert-internal.c File Reference

#include "aes-internal.h"
#include "macros.h"

Go to the source code of this file.

Macros
#define	MIX_COLUMN(T, key)
#define	SWAP(a, b)   do { uint32_t t_swap = (a); (a) = (b); (b) = t_swap; } while(0)

Functions
void	_nettle_aes_invert (unsigned rounds, uint32_t *dst, const uint32_t *src)

Variables
static const uint32_t	mtable [0x100]

Macro Definition Documentation

MIX_COLUMN

#define MIX_COLUMN	(		T,
			key
	)

Value:

    do { \
    uint32_t _k, _nk, _t;   \
    _k = (key);         \
    _nk = T[_k & 0xff];     \
    _k >>= 8;           \
    _t = T[_k & 0xff];      \
    _nk ^= ROTL32(8, _t);   \
    _k >>= 8;           \
    _t = T[_k & 0xff];      \
    _nk ^= ROTL32(16, _t);  \
    _k >>= 8;           \
    _t = T[_k & 0xff];      \
    _nk ^= ROTL32(24, _t);  \
    (key) = _nk;        \
  } while(0)

Definition at line 118 of file aes-invert-internal.c.

SWAP

#define SWAP	(		a,
			b
	)		do { uint32_t t_swap = (a); (a) = (b); (b) = t_swap; } while(0)

Definition at line 135 of file aes-invert-internal.c.

Function Documentation

_nettle_aes_invert()

void _nettle_aes_invert	(	unsigned	rounds,
		uint32_t *	dst,
		const uint32_t *	src
	)

Definition at line 139 of file aes-invert-internal.c.

{
  unsigned i;
 
  /* Reverse the order of subkeys, in groups of 4. */
  /* FIXME: Instead of reordering the subkeys, change the access order
     of aes_decrypt, since it's a separate function anyway? */
  if (src == dst)
    {
      unsigned j, k;
 
      for (i = 0, j = rounds * 4;
       i < j;
       i += 4, j -= 4)
    for (k = 0; k<4; k++)
      SWAP(dst[i+k], dst[j+k]);
    }
  else
    {
      unsigned k;
 
      for (i = 0; i <= rounds * 4; i += 4)
    for (k = 0; k < 4; k++)
      dst[i+k] = src[rounds * 4 - i + k];
    }
 
  /* Transform all subkeys but the first and last. */
  for (i = 4; i < 4 * rounds; i++)
    MIX_COLUMN (mtable, dst[i]);
}

References dst, i, k, MIX_COLUMN, mtable, src, and SWAP.

Referenced by nettle_aes128_invert_key(), nettle_aes192_invert_key(), and nettle_aes256_invert_key().

Variable Documentation

mtable

const uint32_t mtable[0x100]

static

Definition at line 50 of file aes-invert-internal.c.

Referenced by _nettle_aes_invert().