/**
* The code for this function was translated to PHP from mcrypt's enigma.c,
* I was not able to find sufficient documentation to create my own
* version of this function.
* Enigma requires a 13 byte key, this function will
* lengthen the key to get it to 13 bytes long if it's short. It also
* Sets $deck, and $t1, $t2, $t3 which I think are the Enigma rotors.
*
* @return void
*/
private function createKey()
{
$this->deck = array();
$this->t1 = array();
$this->t2 = array_fill(0, self::ROTORSZ, 0);
$this->t3 = $this->t2;
$this->xkey = $this->key();
$klen = $this->keySize();
// get the key to exactly 13 bytes if it's less than 13
if ($klen < 13) {
$this->xkey = str_pad($this->xkey, 13, chr(0), STR_PAD_RIGHT);
}
$seed = 123;
for ($i = 0; $i < 13; ++$i) {
$seed = parent::sInt32($seed) * ord($this->xkey[$i]) + $i;
}
// sets $t1 and $deck
for ($i = 0; $i < self::ROTORSZ; ++$i) {
$this->t1[] = $i;
$this->deck[] = $i;
}
// sets $t3
for ($i = 0; $i < self::ROTORSZ; ++$i) {
// make sure the return values are 32 bit
$seed = 5 * parent::sInt32($seed) + ord($this->xkey[$i % 13]);
$seed = parent::sInt32($seed);
// force the returned value to be an unsigned int
//$random = parent::uint32($seed % 65521);
$random = parent::uInt($seed % 65521);
$k = self::ROTORSZ - 1 - $i;
$ic = ($random & self::MASK) % ($k + 1);
// make sure the returned value is an unsigned int
$random = parent::uInt($random >> 8);
$temp = $this->t1[$k];
$this->t1[$k] = $this->t1[$ic];
$this->t1[$ic] = $temp;
if ($this->t3[$k] != 0) {
continue;
}
$ic = ($random & self::MASK) % $k;
while ($this->t3[$ic] != 0) {
$ic = ($ic + 1) % $k;
}
$this->t3[$k] = $ic;
$this->t3[$ic] = $k;
}
// sets $t2
for ($i = 0; $i < self::ROTORSZ; ++$i) {
$pos = $this->t1[$i] & self::MASK;
$this->t2[$pos] = $i;
}
// now convert $t1, $t2, $t3, $deck values to signed chars,
// PHP's chr() function returns an unsigned char, so we have
// to use use our own
$this->t1 = array_map("parent::sChar", $this->t1);
$this->t2 = array_map("parent::sChar", $this->t2);
$this->t3 = array_map("parent::sChar", $this->t3);
$this->deck = array_map("parent::sChar", $this->deck);
}
