Magnetic Field-Induced STT-MRAM Read Noise for High-Entropy True RNG

A True Random Number Generator (TRNG) is a crucial security component in secure systems, used to generate cryptographic keys and nonces for strong encryption and authentication. Traditional CMOS-based TRNGs, including those based on cross-coupled inverter metastability, transistor oxide breakdown [1], and stochastic switching [2] of Magnetic Tunnel Junctions (MTJs), have been extensively studied. Among these designs, MTJ-based TRNGs offer the best performance, as they do not require additional circuitry and achieve high throughput due to their fast operational speed. Additionally, a recent study demonstrated that Spin-Transfer-Torque Magnetoresistive Random-Access Memory (STT-MRAM) is sensitive to external magnetic fields [3]. In this study, we experimentally demonstrate that a Commercial-Off-The-Shelf (COTS) STT-MRAM can reliably generate random numbers under a magnetic field-driven approach.