STT-ANGIE: Asynchronous True Random Number GEnerator Using STT-MTJ

The Spin Transfer Torque Magnetic Tunnel Junction (STT-MTJ) is an emerging memory technology whose interesting stochastic behavior might benefit security applications. In this paper, we leverage this stochastic behavior to construct a true random number generator (TRNG), the basic module in the process of encryption key generation. Our proposed TRNG operates asynchronously and thus can use small and fast STT MTJ devices. As such, it can be embedded in low-power and low-frequency devices without loss of entropy. We evaluate the proposed TRNG using a numerical simulation, solving the Landau-Lifshitz-Gilbert (LLG) equation system of the STT-MTJ devices. Design considerations, attack analysis, and process variation are discussed and evaluated. The evaluation shows that our solution is robust to process variation, achieving a Shannon-entropy generating rate between 99.7Mbps and 127.8Mbps for 90% of the instances.