Code Changes

		$difference = strlen($string_a) != strlen($string_b);

		// Return if input variables are not strings or if length does not match
		if (!is_string($string_a) || !is_string($string_b) || strlen($string_a) != strlen($string_b))
		{
			return false;
		}

		// Use hash_equals() if it's available
		if (function_exists('hash_equals'))
		{
			return hash_equals($string_a, $string_b);
		}

		$difference = 0;

			$difference |= $string_a[$i] != $string_b[$i];

			$difference |= ord($string_a[$i]) ^ ord($string_b[$i]);