CA-Based Countermeasure for Ascon-128

Abstract

Ascon is a family of lightweight, NIST-standardized authenticated encryption with associated data (AEAD) algorithm designed for resource-constrained environments such as IoT and embedded systems. It was selected as the winner of the NIST Lightweight Cryptography competition (2019–2023) due to its efficiency, high performance, and resistance to side-channel attacks. However, such constrained devices remain vulnerable to implementation-based attacks, particularly fault injection attacks. Joshi and Mazumdar (2021) demonstrated the effectiveness of the Subset Fault Analysis (SSFA) attack on Ascon, showing that the key search space can be reduced from $2^{128}$ to $2^{64}$ under various bit-reset fault models. This result highlights Ascon’s susceptibility to fault-based cryptanalysis. To address this issue, Ambili and Jose (2022) proposed a countermeasure based on a PRNG function constructed using linear cellular automata to enhance fault resistance. In this work, we show that the CA-based Ascon design proposed by Ambili and Jose (2022) remains vulnerable to SSFA attacks and does not completely eliminate the associated security risks. To overcome this limitation, we propose an improved cellular automata-based countermeasure that further strengthens the resistance of Ascon against SSFA attacks. Experimental evaluation using the FELICS framework demonstrates that the proposed approach achieves improved security with minimal overhead.