A Multi-Chaotic Key Expansion for Advanced Encryption Standard (AES) Algorithm

Block cipher-based cryptography employs ciphers dependent on the key for both encryption and decryption. The effectiveness of these systems is contingent on the security and speed of the algorithm. For resilience against cryptanalytic attacks, the encryption process must exhibit adaptability and dynamism. The Advanced Encryption Standard (AES) stands out as the most recommended symmetric key block cipher for securing data in sensitive networks and applications. Traditional key expansion methods in AES typically rely on fixed approaches, maintaining the same expansion mode consistently throughout the encryption process. Each cipher undergoes multiple rounds with fixed operations to achieve the desired level of security. In this paper, the study presents a novel and efficient algorithm that improves the existing AES algorithm by employing the Lorenz attractor and Chen attractor for key generation. The chaotic outputs from the Lorenz attractor and Chen attractor are employed to adjust the substitution box (S-box) operations and key mixing operations, respectively. The experimental result demonstrates that the Multi-Chaotic AES significantly improves security compared to the original AES.