/**
* Cast 128 F3 function
*
* @param $r integer The right half of the data being encrypted in cast_128()
* @param $i integer The round number (1-16) in cast_128()
* @return integer The value after the F3 transformation
*/
private function f3($r, $i)
{
$n = $this->_mkey[$i] - $r;
$n = parent::uInt32(parent::rotBitsLeft32($n, $this->_rkey[$i]));
$n = parent::dec2Str($n, 4);
$f = parent::uInt32((self::$_s1[ord($n[0])] + self::$_s2[ord($n[1])] ^ self::$_s3[ord($n[2])]) - self::$_s4[ord($n[3])]);
return $f;
}
/**
* CAST-256 F3 function
*
* @param $d integer The the data input
* @param $m integer The 32 bit masking key
* @param $r integer The round number
* @return integer The value after the F3 calculation
*/
private function f3($d, $m, $r)
{
$n = parent::uInt32($m - $d);
$n = parent::uInt32(parent::rotBitsLeft32($n, $r));
$n = parent::dec2Str($n, 4);
return parent::uInt32((self::$_s1[ord($n[0])] + self::$_s2[ord($n[1])] ^ self::$_s3[ord($n[2])]) - self::$_s4[ord($n[3])]);
}
