Many UAV technology use cases (e.g., traffic management) has ultra-low latency and strong security requirements. But achieving both simultaneously is challenging. In this work, we consider UAV device authentication as a use case and develop a fast and secure UAV device authentication system. Our key idea is to leverage highly secure Physically Unclonable Functions (PUFs) and high-speed programmable packet-processing data planes, and develop a practically deployable PUF-based authentication protocol for UAVs that is (a) robust to various security attacks, and (b) enables UAV authentication at network speed. In this work, we demonstrate the feasibility of our idea by offloading the authentication protocol to a Tofino-based highspeed programmable switch. Our preliminary experiments show that protocol offloading would reduce authentication latency significantly (approx. 100 %).