CHIMA: Design and Evaluation of a Lightweight Cryptographic System for IoT Applications

Resource-constrained Internet of Things (IoT) devices motivate the investigation into cryptographic designs with measurable implementation costs. This work presents CHIMA (Cryptography cHaotic lIghtweight systeM and Authentication), an experimental system combining a key generator based on chaotic states, a Feistel cipher using the AES substitution box and a keyed bit permutation, and a Lesamnta-LW-based ciphertext check. Logistic, H'enon, and Lorenz systems are examined for key generation, and cipher variants with 64-bit and 128-bit blocks are evaluated. The study reports functional tests, avalanche measurements, NIST statistical tests, and implementation measurements on Arm Cortex-M0+, Cortex-M33, and Cortex-M7 microcontrollers. Controlled WiFi/MQTT and LoRa experiments assess communication interoperability. The results show that the chaotic key generator achieved high entropy and passed all NIST statistical tests, indicating its suitability for generating pseudorandom sequences. Based on the combined encryption and decryption times, CHIMA-64 requires 57.95-64.16% less time than PRESENT, while CHIMA-128 requires 23.60-59.36% less time than AES-128 and 13.32-47, as well as 10% less time than CLEFIA across the three platforms.