STT-MRAM-based PUF architecture exploiting magnetic tunnel junction fabrication-induced variability

Physically Unclonable Functions (PUFs) are emerging cryptographic primitives used to implement lowcost device authentication and secure secret key generation. Weak PUFs (i.e., devices able to generate a single signature or to deal with a limited number of challenges) are widely discussed in literature. One of the most investigated solutions today is based on SRAMs. However, the rapid development of low-power, high-density, high-performance SoCs has pushed the embedded memories to their limits and opened the field to the development of emerging memory technologies. The Spin-Transfer-Torque Magnetic Random Access Memory (STT-MRAM) has emerged as a promising choice for embedded memories due to its reduced read/write latency and high CMOS integration capability. In this article, we propose an innovative PUF design based on STT-MRAM memory. We exploit the high variability affecting the electrical resistance of the Magnetic Tunnel Junction (MTJ) device in anti-parallel magnetization. We will demonstrate that the proposed solution is robust, unclonable, and unpredictable.