Research Article An Efficient Lightweight Cryptographic Instructions Set Extension for IoT Device Security WajihElHadjYoussef ,AliAbdelli,FethiDridi,RimBrahim,andMohsenMachhout Faculty of Sciences of Monastir, Electronics and Micro-Electronic Laboratory (LEME), Monastir 5000, Tunisia Correspondence should be addressed to Wajih El Hadj Youssef; elhadjyoussef.wajih@gmail.com Received 5 June 2021; Revised 6 December 2021; Accepted 4 January 2022; Published 5 February 2022 Academic Editor: Ricardo Chaves Copyright © 2022 Wajih El Hadj Youssef et al. is is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. e Internet of ings is changing all sectors such as manufacturing, agriculture, city infrastructure, and the automotive industry. All these applications ask for secure processors that can be embedded in the IoTdevices. Furthermore, these devices are restricted in terms of computing capabilities, memory, and power consumption. A major challenge is how to meet the need for security in such resource-constrained devices. is paper presents a customized version of LEON3, the ReonV RISCV (Reduced Instruction Set Computer-five) processor, dedicated for IoT applications that has strong effective security mechanisms built in at the design stage. Firstly, efficient lightweight cipher designs are elaborated and validated. en, the proposed cryptographic instructions (PRESENTand PRINCE) are integrated into the default instruction set architecture of the ReonV processor core. e instruction set extensions (ISE) of lightweight cipher modules can be instantiated in software routines exactly as the instructions of the base architecture. A single instruction is needed to implement a full lightweight cryptographic instruction. e customized ReonV RISCV processor is implemented on a Xilinx FPGA platform and is evaluated for Slice LUTs plus FF-pairs, frequency, and throughput. Obtained results show that our proposed concepts not only can achieve good encryption results with high per- formance and reduced cost but also are secure enough to resist against the most common attacks. 1.Introduction e Internet of ings (IoT) refers to a huge number of connected devices to the Internet, all collecting and sharing vast amounts of data [1]. Regarding the huge amount of connected devices, the IoT has become an integral part of the lives of billions of people around the world. However, when using open and connected devices such as smart city assets like smart transportation, smart traffic- lights, and smart meters, in industry 4.0 devices like pro- grammable logic controllers (PLCs), robots, and machines, there have been recently many IoT-related security threats with a devastating security incident and the problems will get worse [2, 3]. Hence, we all have to make security the key issue in the choice and deployment of IoT-related devices. Cryptography is an effective countermeasure, and the IoT is now required to apply encryption to autonomous devices in environments with various restrictions. Lightweight cryptography is a technology researched and developed to enable the application of secure encryption, even for devices with limited resources [4]. Securing IoTdevices require innovation at the processor level to boost the next generation of IoT edge devices with a new kind of enhanced processors. is category of pro- cessors is built on new levels of Central Processing Unit (CPU) with integrated IoT features, real-time performance, and functional safety. Security mechanism can be added to processor based IoT devices by means of specific software libraries or dedicated hardware accelerators. e software approach is very flexible, but it is not suited for extremely constrained devices. Indeed, software solution can be too costly in terms of memory occupation or energy con- sumption and the performance may be enough to meet the application requirements. Moreover, certain security threats may not be defeated using software solutions only. e second approach allows meeting better performance and Hindawi Security and Communication Networks Volume 2022, Article ID 9709601, 17 pages https://doi.org/10.1155/2022/9709601