A multicolor carbon dot doped nanofibrous membrane for unclonable anti-counterfeiting and data encryption

Abstract

In modern security, devices, individuals, and communications require unprecedentedly unique identifiers and cryptographic keys. One emerging method for guaranteeing digital security is to take advantage of a physical unclonable function (PUF). Paper PUF has been extensively demonstrated as a hidden security for a wide range of paper documents and packaging. However, the readout of the existing paper PUF is far less robust and has a smaller key storage capacity. Therefore, we propose using electrospinning as a universal technique to fabricate a strong, in-built and high-capacity PUF based on the random morphologies of electrospun nanofibers (ESNFs). To achieve a high key space within a given sensor, multicolor carbon dots are adopted to label individual fibers to create four independent challenge–response pairs: dark-field scattering, fluorescent red, green and blue emissions. Through a modified perceptional hashing, each ESNF-PUF sensor generates a 256-bit fingerprint per challenge–response pair. A bitstream of 300 Kbits from 48 PUF sensors passes all of thirteen NIST randomness tests without any post-processing. The entropy of the fingerprint is estimated to be 246 bits, resulting in a key space of 5²⁴⁶, simultaneously the false positive rate is below 10⁻⁹, and more than 102.4 Mbit cm⁻² binary keys are generated from the ESNF-PUFs, providing an enormous address space for one-time pad applications. The conciseness of fingerprints has also been investigated, revealing a trade-off between the entropy and robustness of the PUF system. For practical application, the signature and authentication process of the secured paper document derived by electrospinning are demonstrated. In addition, the ESNF-PUF could be used as a chaotic system to encrypt and decrypt the data robustly.