Magnetic tunnel junction as a real-time entropy source: Field-Programmable Gate Array based random bit generation without post-processing

TL;DR

This paper presents a FPGA-based method using magnetic tunnel junctions to generate true random bits in real-time at 5 Mbps, eliminating the need for post-processing and ensuring compliance with NIST standards.

Contribution

It introduces a novel real-time feedback and XOR-based stabilization technique for magnetic tunnel junctions to produce high-quality random bits without post-processing.

Findings

Achieved NIST-compliant random bit generation at 5 Mbps

Implemented real-time feedback loop to stabilize switching probability

Demonstrated suppression of correlations and bias in the bitstream

Abstract

We demonstrate a method to generate application-ready truly random bits from a magnetic tunnel junction driven by a Field-Programmable Gate Array (FPGA). We implement a real-time feedback loop that stabilizes the switching probability near 50\% and apply an XOR operation, both on the FPGA, to suppress short-term correlations, together mitigating long-term drift and bias in the bitstream. This combined approach enables NIST-compliant random bit generation at 5~Mb/s without post-processing, providing a practical hardware solution for fast and reliable true random number generation. Beyond cryptographic applications, these capabilities open opportunities for stochastic hardware accelerators, probabilistic computing, and large-scale modeling where real-time access to unbiased randomness is essential.