function _setupKey()
{
if (!isset($this->key)) {
$this->setKey('');
}
// Key has already been expanded in \phpseclib\Crypt\RC2::setKey():
// Only the first value must be altered.
$l = unpack('Ca/Cb/v*', $this->key);
array_unshift($l, $this->pitable[$l['a']] | $l['b'] << 8);
unset($l['a']);
unset($l['b']);
$this->keys = $l;
}