Abstract
In this paper, proposed a hybrid multi-factor authentication (MFA) method to secure and enhance performance in resource-constrained environments, such as IoT and embedded devices. The strategy combines deterministic finite automata (DFA) for formal state-based control of authentication, chaotic key generation based on the Lorenz dynamical system, and the ChaCha20 stream cipher for lightweight encryption. In research, security threats are rapidly increasing with distributed deployments, and traditional MFA models, which often lack formal verification mechanisms and impose computationally heavy complexities, are inadequate. The proposed model overcomes these limitations by introducing a deterministic authentication flow, ensuring strict state transitions and resistance to replay attacks. This approach deals with formally modeling the authentication mechanism via DFA, numerically simulating Lorenz to compute cryptographic key generation for, and implementing ChaCha20. Experimental results confirm the proposed solution provides an extremely low execution time and faster throughput than the AES-based approach, thus is suitable for low-power devices. Furthermore, chaotic systems improve entropy and provide robustness to brute-force attacks. This research confirms that this hybrid model balances security, computing efficiency, and formal verification requirements. This method is promising for IoT, mobile authentication, and distributed secure systems.