A Lightweight True Random Number Generator for Root of Trust Applications

There are many schemes proposed to protect integrated circuits (ICs) against an unauthorized access and usage, or at least to mitigate security risks. They lay foundations for hardware roots of trust whose crucial security primitives are generators of truly random numbers. In particular, such generators are used to yield one-time challenges (nonces) supporting the IC authentication protocols employed to counteract potential threats such as untrusted users accessing ICs. However, IC vendors raise several concerns regarding the complexity of these solutions, both in terms of area overhead, the impact on the design flow, and testability. These concerns have motivated this work presenting a simple, yet effective, all-digital lightweight and self-testable random number generator to produce a nonce. It builds on a generic ring generator architecture, i.e., an area and time optimized version of a linear feedback shift register, driven by a multiple-output ring oscillator. A comprehensive evaluation, based on three statistical test suits from NIST and BSI, show feasibility and efficiency of the proposed scheme and are reported herein.