Physical Unclonable Functions – Past, Present and Future

Physical Unclonable Function (PUF) has emerged as an inexpensive security primitive to overcome the device identification and authentication problems by its radically different way of interrogating hardware without the permanent presence of a secret key. The security of PUF rests in the intrinsic complexity and irreproducibility of a random physical disorder system instead of a hard-to-solve mathematical problem. Device signature generated by PUF cannot be physically replicated even by the original manufacturer due to the uncontrollable nature of manufacturing process variations. As the secret information can only be generated when the PUF is powered on, active manipulation of circuit structure will cause dysfunction of its challenge-response mechanism and become tamper evident. As unique and unclonable chip identifiers, PUFs find its niche in active hardware metering, which enables chip designers to lock and unlock the circuit functionality to gain post-fabrication control of their intellectual property and clone detection. Besides, rich variety of post-CMOS technologies, such as Phase Change Memory and Spin Transfer Torque Magnetic Random Access Memory, offer new challenges and opportunities to PUF system design. Last but not least, sensors are integral parts of an IoT ecosystem for life-changing applications. Integration of PUF credentials into sensor circuitry or sensing data without compromising the original sensing operations holds strong promises in addressing forensic and security problems in IoT.