Lightweight and Fault-Resilient Implementations of Binary Ring-LWE for IoT Devices

While the Internet of Things (IoT) shapes the future of the Internet, communications among nodes must be secured by employing cryptographic schemes such as public-key encryption (PKE). However, classic PKE schemes, such as RSA and elliptic curve cryptography (ECC) suffer from both high complexity and vulnerability to quantum attacks. During the past decade, post-quantum schemes based on the learning with errors (LWEs) problem have gained high attention due to the lower complexity among PKE schemes. In addition to resistance against theoretical (quantum and classic) attacks, every practical implementation of any cryptosystem must also be evaluated against different side-channel attacks such as power analysis or fault injection ones. In this article, we analyze the vulnerability of binary ring learning with error (Ring-LWE) scheme regarding (first-order) fault attacks, such as randomization, zeroing, and skipping faults. We show that previous implementations can be easily broken by employing such fault attacks. Moreover, we propose fault-resilient software implementations of binary Ring-LWE on 8- and 32-b lightweight microcontrollers, namely, AVR ATxmega128A1 and ARM Cortex-M0 that are ideal for IoT devices. Furthermore, we formally prove the resilience of the proposed implementations against different fault attacks. To the best of our knowledge, this article is the first one to propose fault-resilient binary Ring-LWE implementations on resource-constrained microcontrollers. Our implementations on AVR ATxmega128A1 require only 80 and 120 ms for encryption and decryption, respectively.