SOT-MTJ-Based Non-Volatile Flip-Flop With In-Memory Randomness for Application in Grain Stream Ciphers
Arshid Nisar, Furqan Zahoor, Sidhaant Sachin Thakker, Kunal Kranti Das, Subhamoy Maitra, Brajesh Kumar Kaushik, Anupam Chattopadhyay · IEEE Access · 2025
This paper proposes a method for in-memory true random number generation (TRNG) by leveraging the dual functionality of spin-orbit torque based magnetic tunnel junction (SOT-MTJ) while showcasing its efficacy in hardware-efficient Grain stream ciphers for lightweight cryptographic applications. Depending upon its mode of operation, SOT-MTJ acts as both a memory element and a true random number generator. To demonstrate its practical application, SOT-MTJ based non-volatile flip flop (NVFF) is designed which is further utilized to implement Grain-128 stream cipher, as a case study. The SOT-MTJ based NVFF not only carries out the standard shift operation for cipher implementation but also functions as an in-situ initial vector generator for generating key stream, eliminating the need for an additional TRNG circuit. The results show that the proposed Grain-128 cipher design is$5.6\times $and$2.5\times $more energy efficient and$5\times $and$2\times $faster as compared to STT and SOT-MTJ based designs. Furthermore, in comparison to CMOS based cipher design, the proposed technique shows nearly$\sim 34\times $more efficiency in terms of area overhead. The proposed approach holds huge promise for resource-constrained cryptographic applications in edge devices.