/**
* Applies the Sbox to each byte of the string passed in.
* This is similar to subByte(), but Unlike subByte() we do not use
* the _s_inv[] table. This function is only used in expandKey(),
* which is implemented by the class that inherits this class
*
* @param string $text The string to peform the byte subsitution
* @return string The string with the subsituted bytes
*/
private function subWord(&$text)
{
$max = strlen($text);
for ($i = 0; $i < $max; ++$i) {
// the sbox is arrange in a 16 x 16 grid, where each row
// and column is numbered in hex (from 0 - f)
$hex = parent::str2Hex($text[$i]);
$row = parent::hex2Dec($hex[0]);
$col = parent::hex2Dec($hex[1]);
$pos = $row * 16 + $col;
$text[$i] = chr(self::$_s[$pos]);
}
}
