Stochastic resistive switching in memristors as physically unclonable functions

Memristors are promising candidates for generating physically unclonable functions (PUFs) due to their inherently stochastic resistive switching behaviors. In memristive devices, conducting paths are formed via charge trapping, ion migration, or filamentary conduction mechanisms across the active region, resulting in arbitrary resistive switching characteristics. To harness memristors for PUF applications, it is essential to enhance the entropy sources associated with device operation to optimize randomness, uniqueness, and diffuseness. In this review, we elucidate the fundamental mechanisms underlying resistive switching in memristors, with a focus on factors contributing to their stochastic characteristics. Recent strategies to enhance randomness, ranging from material and device-level engineering to external circuit algorithms, are also discussed. Furthermore, practical applications of memristor-based PUFs, including cryptographic key generation, data encryption, and random data generation, are introduced. Finally, we outline future research directions for advancing memristor-based PUFs toward widespread deployment across diverse application domains.