Evaluation of SRAM PUF Characteristics and Generation of Stable Bits for IoT Security

Abstract

Better security is essential for IoT devices these days. Device authentication of IoT devices can be done by using Static Random-Access Memory Physical Unclonable Functions (SRAM PUF). However, SRAM PUF has poor stability and relatively high error rate. Temporal Majority Voting (TMV) and other Error Correction Codes (ECCs) has been used to improve SRAM PUF performance. But they require a lot of processing time and hardware resources. Most of the microcontrollers used in IoT devices do not have that. Still, those methods cannot produce sufficiently stable bits of SRAM PUF. The data remanence nature of SRAM cells can be utilized to generate much more stable SRAM PUF with low error rates. In this paper, we made use of both TMV and data remanence to obtain SRAM PUF characteristics of microcontrollers used in IoT devices. The characteristics of SRAM PUF such as biasness, uniqueness and stability have been analyzed and investigated for better understanding of SRAM PUF on different chips. Moreover, by using the data remanence method, we managed to obtain 128 bits of SRAM PUF from 512 bits of initial SRAM values with the error rate of 3.77 × 10⁻⁸ and the stability of 99.983% which can be implemented on simple microcontrollers.