LESCA: LightwEight Stream Cipher Algorithm for emerging systems

Recently, there has been a dire need for lightweight cryptographic solutions, which exhibit low computational complexity and require few resources. In this paper, we present LESCA, a novel dynamic key-dependent lightweight stream cipher, which consists of two main functions, a typical round function based on cryptographic primitives, and a function that updates these primitives. The update is performed in a selective (partial) manner while encrypting a block, and in full after each δ blocks/iterations. As such, LESCA consumes minimal resources and introduces a very low latency. The originality of this solution stems from the fact that the cryptographic primitives get updated even when encrypting the same message. Several performance and security tests were performed to confirm that the proposed cipher is robust and efficient, especially for limited devices and real-time applications. The proposed cipher achieves a high throughput; for example, when implemented on a Raspberry Pi (RPI4) device, LESCA provides an enhancement of at least 343% when compared to the Advanced Encryption Standard (AES), 72% over a recent one-round cipher scheme, and 43% improvement compared to a recent LORCA stream cipher that outperforms the Simon and Speck algorithms.