Date of Award

May 2022

Degree Type


Degree Name

Doctor of Philosophy



First Advisor

Weizhong Wang

Committee Members

Yi Hu, Jun Zhang, Zeyun Yu, Robert Turney


Field Programmable Gate Array, Hardware security, Identification and Authentications, Physical Unclonable Features, Secure root sources


The Physical Unclonable Functions (PUFs) is a candidate to provide a secure solid root source for identification and authentication applications. It is precious for FPGA-based systems, as FPGA designs are vulnerable to IP thefts and cloning. Ideally, the PUFs should have strong random variations from one chip to another, and thus each PUF is unique and hard to replicate. Also, the PUFs should be stable over time so that the same challenge bits always yield the same result. Correspondingly, one of the major challenges for FPGA-based PUFs is the difficulty of avoiding systematic bias in the integrated circuits but also pulling out consistent characteristics as the PUF at the same time. This thesis discusses several compact PUF structures relying on programmable delay lines (PDLs) and our novel intertwined programmable delays (IPD). We explore the strategy to extract the genuinely random PUF from these structures by minimizing the systematic biases. Yet, our methods still maintain very high reliability. Furthermore, our proposed designs, especially the TERO-based PUFs, show promising resilience to machine learning (ML) attacks. We also suggest the bit-bias metric to estimate PUF’s complexity quickly.