Design of a True Random Number Generator Based on MRAM Devices

Cryptographic schemes heavily rely on reliable random number generators. In a wide range of key generation schemes, such as the ones considered for post-quantum cryptography, cryptographic keys must be generated with random numbers that opponents cannot guess. Pseudo-random numbers (PRNs) are based on mathematical formulas, making them highly vulnerable to attacks. The generation of true random numbers (TRNs) can be achieved through various physical devices, including sensors, thermal noise generators, and many other components with high levels of stochasticity. A true random number generator (TRNG), even though it is slower, can generate non-deterministic data, making it highly secure. Magneto-resistive random access memories (MRAM), due to their high speed, non-volatility, high reliability, low fabrication cost, and low power consumption, are viable candidates for the design of cryptographic keys and true random numbers. The purpose of the work presented in this paper has been to exploit the physical characteristics of MRAMs to design true random numbers. We propose hardware and software implementations of TRNG schemes. We test random sequences using the statistical test suite from the National Institute of Standards and Technology (NIST) for random and pseudo-random numbers. Furthermore, we propose a post-processing method that uses XORing with pseudo-random numbers to improve randomness and security.