frames.php
public function getAuthentication()
    {
        if (is_integer($this->focus)) {
            return $this->frames[$this->focus]->getAuthentication();
        }

        return $this->frameset->getAuthentication();
    }
public function getAuthentication()
    {
        if (is_integer($this->focus)) {
            return $this->frames[$this->focus]->getAuthentication();
        }

        return $this->frameset->getAuthentication();
    }
Accessor for last Authentication type. Only valid straight after a challenge (401).

@return string    Description of challenge type.