TCASKD: A Lightweight Hybrid Cryptosystem Using Tent Map and Cellular Automata for Secure Shared‐Key Derivation

ABSTRACT This work presents a lightweight hybrid cryptosystem, Tent Map and Cellular Automata‐based Secure Shared‐Key Derivation (TCASKD), for secure image encryption in resource‐constrained environments. TCASKD uses the chaotic behavior of the Tent Map to generate high‐entropy sequences and applies a one‐dimensional CA rule vector to efficiently transform key streams. A dynamic S‐box generated from chaotic sequences ensures intense confusion, while CA diffusion spreads pixel changes and enhances randomness. The experimental results show that TCASKD achieves a number of pixels change rate (NPCR) of 99.7611%, a unified average changing intensity (UACI) of 33.3671%, an information entropy of 7.9994, a very low correlation of 0.0014, and a processing speed of 9.18 MB/s. The results, along with the theoretical analysis against differential, chosen‐plaintext, and side‐channel attacks, confirm that TCASKD offers strong resistance to both statistical and cryptanalytic attacks while maintaining high performance.