a lightweight 64-bit symmetric block cipher, called SIT, whose implementation is a mixture of Feistel and a uniform substitution-permutation network. The proposed approach uses some logical operations along with some swapping and substitution. Most of the encryption algorithms designed for IoT reduced the number of rounds to make a cost-security trade-off. For instance, SIT uses five rounds of encryption with 5 different keys to improve energy efficiency.

The lightweightedness of the stream ciphers, on the other hand, has received fascinated attention from many researchers’ in recent years [@mohd2015survey; @singh2017advanced; @sfar2018roadmap; @manifavas2016survey]. Since IoT being an emerging field requires lightweight cipher designs with robustness, less complexity, and lower energy consumption, stream ciphers are very suited for particularly edge devices. Many studies evaluate the possibility of engaging stream ciphers in IoT devices, such as WG-8 [@fan2013wg], Trivium [@de2005trivium], Quavium [@tian2012quavium], and ACORN [@wu2016acorn].

*ExTru* Infrastructure {#sec:proposed}
======================

*ExTru* consists of four main sub-modules: (1) ACORN as a stream cipher that would be used periodically (The frequency will be discussed further), (2) a configurable switching and toggling network (CSTN) that dynamically permutes/toggles the data based on the configuration generated by TRNG, (3) a random number generator (RNG) that is responsible for generating random 