The volume of data transmitted over networks has significantly increased in recent years. For that reason, safeguarding the privacy, authenticity, and confidentiality of specific data is imperative, necessitating a type of encryption; symmetric encryption, known for its computational efficiency, is ideal for securing extensive datasets. A principal component within symmetric key algorithms is the substitution box (S-box), which creates confusion between plaintext and ciphertext, enhancing the security of the process. This paper proposes a fashion method to create chaotic S-boxes using the Rössler attractor as a chaotic process and the Rijndael S-box as a permutation box. The proposed S-boxes are evaluated with bijectivity, non-linearity (NL), strict avalanche criterion (SAC), bit independence criterion (BIC), linear approximation probability (LAP), and differential uniformity (DU). The analyses show that the proposed method helps generate a high-resistance S-box to well-known attacks and high efficiency, executing in short computational time.

In this paper, a security framework based on cellular automata is proposed, which is composed of three parts: entity authentication, data encryption, and decryption. Authentication is based on a zero-knowledge protocol, and its robustness is supported by the fact that the shared secret is not only an NP-complete problem but also dynamically transformed by a two-dimensional cellular automaton into a more complex secret. Thus, the authentication’s output is the key to data encryption/decryption in the following steps. One more strength of this system is the sensibility of the cellular automata to initial conditions—which is why we must know the initial configuration in order to obtain the key and the times that cellular automata evolved. All those characteristics give the system both robustness and security.