Implementation of SIMON and SPECK lightweight block ciphers on programmable logic controllers

Programmable Logic Controllers (PLCs) are the key components of SCADA systems, controlling different industrial processes, while handling the communication with other systems via different communication protocols, which are subject to security attacks. The introduction of cryptography at the PLC's application level could represent a first step in providing the needed security for such systems. However, despite the recent technological progress, PLCs are still quite limited equipment in terms of processing performance, when compared to other computing systems (e.g., PCs). Consequently, running the traditional cryptographic algorithms at PLC level is time consuming and requires a lot of resources. In this context, the implementation of the recent lightweight cryptographic algorithms may provide more feasible solutions. This paper presents the PLC implementation aspects and the results for the SIMON and SPECK families of cryptographic algorithms, as tested on Phoenix Contact's ILC 350 PN controller.