RUST-Encoded Stream Ciphers on a RISC-V Parallel Ultra-Low-Power Processor

Nowadays, the development of security applications is a relevant topic in the Internet of Things (IoT) and cyber-physical systems (CPS) fields. Different embedded architectures have been adopted in these areas, but the RISC-V parallel ultra-low-power (PULP) architecture stands out as a particularly efficient system. However, it has never been proposed to enable cryptography. In the context of video stream security, stream ciphers enable an efficient solution to ensure data privacy, and the exploitation of the PULP multi-core accelerator cluster paves the way to an efficient implementation of these ciphers. In this paper, we exploit the capability of the PULP architecture coupled with the code safety provided by the RUST programming language to design and implement an efficient stream encryption algorithm. We present a wrapper system between the development libraries of a PULP platform enabling the secure execution of a verified RUST-written implementation of ChaCha20 and AES-CTR, targeting a microdrones based video surveillance system. Experimental tests have resulted in an encryption efficiency of ChaCha20 of 2.3 cycles per Byte (cB), placing the resulting implementation at the state-of-the-art, in direct competition with higher-class architectures like Apple M1 (2.0 cB).