Ultra-low-power ring oscillator based true random number generator for passive UHF RFID tags

• Published in: 2018 IEEE Topical Conference on Wireless Sensors and Sensor Networks (WiSNet) pp. 99 - 102
• Main Authors: Saxl, Georg, Ferdik, Manuel, Ussmueller, Thomas
• Format: Conference Proceeding
• Language: English
• Published: IEEE 01.01.2018
• Subjects: Generators; Integrated circuit modeling; Inverters; Passive RFID tags; Power demand; Ring oscillators
• ISSN: 2473-4624
• DOI: 10.1109/WISNET.2018.8311575

This paper deals with the development of a random number generator for cryptographic key generation. The proposed implementation is designed for the use in a passive UHF RFID Tag and is based on a 55 nm semiconductor process. Since passive RFID Tags are not equipped with an autonomous power supply, the circuit is designed for minimal power consumption. However, the design should still generate a sufficient randomness. When generating keys for cryptographic applications, it must be ensured that there is no way of predicting them. Therefore, a true random number generator (TRNG) is used. The proposed TRNG is based on several ring oscillators, which are subject to random phase noise (jitter). By comparing the positions of the phases, the extraction of the randomness can be performed. Additionally, a post-processing unit is deployed, to increase the randomness of the circuit. To evaluate the randomness of the bit sequences generated by simulation, the NIST Statistical Test Suite is used. The results show a minimal dependence on the randomness of the thermal effects within the specified range. Furthermore, they suggest a likely sufficient randomness of all tested bit sequences. According to simulations, the maximum power consumption of the entire circuit is 270 nW at 27 °C.