Biswarup Yogi, Ajoy Kumar Khan
The present work demonstrates that combining Elliptic Curve Cryptography and Cellular Automata Rule 90 for AES shared session key generation improves randomness, security strength, and computational efficiency. The proposed method uses ECC to generate a shared secret in binary form. CA Rule 90 expands this binary sequence into the key stream. AES then encrypts the input image using this hybrid session key. The system is developed and executed with standard benchmark images in Python. The results show that the mechanism is highly resistant to statistical and differential attacks. For example, the NPCR achieves 99.6916%, UACI reaches 49.5214% with the encrypted images having high entropy and high MSE values with almost no pixel correlation. The method is relatively fast, with an average encryption time of 0.000248 s, and has low memory and CPU utilisation. Based on the presented information, the ECC-CA hybrid model offers an efficient approach for providing lightweight security for IoT and resource-constrained devices.