Enhancing AES Security with the Integration of the Orthogonal Haar Transform

This paper presents a hybrid encryption algorithm that integrates the orthogonal Haar Transform into the Advanced Encryption Standard (AES) framework to enhance cryptographic strength.By inserting the Haar Transform between the SubBytes and ShiftRows stages in AES-128, the proposed scheme increases confusion and diffusion, thereby improving resistance to cryptanalytic attacks.Experimental results were obtained using a fixed 128-bit key and multiple plaintext samples of varying lengths, demonstrating notable improvements in key security metrics.The avalanche effect increased from 61.0% to 73.44%, and the bitwise correlation coefficient decreased from 0.17 to 0.02, indicating nearrandomness in the ciphertext.While the Shannon entropy slightly declined from 3.70 to 3.20 bits per byte due to the orthogonal nature of the transform, the overall unpredictability and structural complexity of the output were enhanced.The integration introduces a modest 7% performance overhead, which remains acceptable for applications prioritizing security, such as embedded systems, IoT devices, and secure cloud storage.The proposed AES-H algorithm offers a practical balance between computational efficiency and enhanced cryptographic robustness.