58 50 42 34 26 18 10 2
60 52 44 36 28 20 12 4
62 54 46 38 30 22 14 6
64 56 48 40 32 24 16 8
57 49 41 33 25 17  9 1
59 51 43 35 27 19 11 3
61 53 45 37 29 21 13 5
63 55 47 39 31 23 15 7

uint64_t des_IP_shuffle(uint64_t v) {
  int i, j;
  uint8_t tmp[8];
  for (i = 0; i < 8; i++) {
    for (j = 0; j < 8; j++) {
      tmp[j] = (tmp[j] << 1) | (v & 1);
      v >>= 1;
    }
  }
  v = 0;
  for (i = 6; i >= 0; i -= 2)
    v = (v << 8) | tmp[i];
  for (i = 7; i >= 0; i -= 2)
    v = (v << 8) | tmp[i];
  return v;
}