A Secure and Robust Key Generation Method Using Physical Unclonable Functions and Polar Codes

In physical unclonable functions (PUFs) based key generation methods, the bias of PUF outputs would leak secrecy. A secure and robust key generation method based on PUFs and polar codes is proposed in this paper. First, a PUF-based key generation process is modeled as a wiretap channel. Then, two secure polar coding schemes are designed for the wiretap channel to improve the robustness of key generation and to reduce the secrecy leakage caused by the bias of PUF outputs. To construct the secure polar coding schemes, density evolution is used to evaluate the error probability of synthesized channels, which in turn is used to approximate both the error probability and the secrecy leakage of the system. To reduce the polar construction complexity, the channel independent polar construction method aids density evolution to select parameters of the secure polar coding schemes. Finally, we compare the key generation design with other works and find that our key generation scheme requires fewer PUF bits than other works when they generate the same length key with failure probability $\le 10^{-6}$.