Disordered Heteronanostructures of MoS₂ and TiO₂ for Unclonable Cryptographic Primitives

In the era of hyperconnected contemporary society, hardware and information security become more dependent on advanced cryptographic primitives. A physically unclonable function (PUF), originally implemented by an algorithmic means as software-based security, is considered as an immediate security solution. Nanomaterial-based PUFs have recently received considerable attention but have often limitations on unclonability and scalability for practical applications. Here, we report that heteronanostructures of vertically orientated molybdenum disulfide (MoS2) nanoflakes and titanium dioxide (TiO2) aggregates can be used for a versatile PUF. The band alignment of heteronanostructured MoS2/TiO2 results in photogenerated electron transfer and turns off the bright state of emitters, offering an entropy source. After von Neumann debiasing, extracted cryptographic keys show a large encoding capacity and reliable PUF performance, including randomness, uniqueness, reproducibility, low false rates, and long-term stability. The unique hybridization of the most common semiconductor nanomaterials could not only offer inherent asymmetry not to be cloned for a PUF but also guarantee scalable nanomanufacturing strategies to augment cryptosystems.