OpenPGP_SignaturePacket::get_subpacket PHP Method

    static function get_subpacket(&$input)
    {
        $len = ord($input[0]);
        $length_of_length = 1;
        // if($len < 192) One octet length, no furthur processing
        if ($len > 190 && $len < 255) {
            // Two octet length
            $length_of_length = 2;
            $len = ($len - 192 << 8) + ord($input[1]) + 192;
        }
        if ($len == 255) {
            // Five octet length
            $length_of_length = 5;
            $unpacked = unpack('N', substr($input, 1, 4));
            $len = reset($unpacked);
        }
        $input = substr($input, $length_of_length);
        // Chop off length header
        $tag = ord($input[0]);
        $class = self::class_for($tag);
        if ($class) {
            $packet = new $class();
            $packet->tag = $tag;
            $packet->input = substr($input, 1, $len - 1);
            $packet->length = $len - 1;
            $packet->read();
            unset($packet->input);
            unset($packet->length);
        }
        $input = substr($input, $len);
        // Chop off the data from this packet
        return $packet;
    }