HSE_515 Hinweis Science and Engineering | Volume 2, Issue 1, January 2025 103 Hinweis Science and Engineering ISSN: 2583-9640 Vol.2, Issue 1, January 2025 Available online at: http://hien.thehinweis.com I. INTRODUCTION In an era where digital audio plays a pivotal role in communication, entertainment, and data storage, ensuring the security of audio content has become a pressing concern. Applications such as secure voice communications, confidential recordings, and protected media distribution require encryption methods that not only safeguard data but also preserve the fidelity of the original audio. While traditional cryptographic algorithms such as the Advanced Encryption Standard (AES) [1] provide strong confidentiality guarantees, they operate primarily in the data domain and do not leverage signal-specific transformations that could enhance protection. The Walsh–Hadamard Transform (WHT) [2] offers unique advantages for audio security. As an orthogonal, reversible transform, it redistributes audio signal energy into a set of discrete Walsh coefficients, effectively scrambling the waveform in a way that is unintelligible to unauthorized parties yet fully recoverable by legitimate recipients. This transformation alone introduces a layer of obfuscation, making intercepted audio far less interpretable even before cryptographic encryption is applied. Previous research has demonstrated that Walsh-based hybrid methods can be successfully applied to text encryption, where Walsh transforms were combined with AES and RSA to enhance diffusion and structural complexity in the ciphertext [3,4,5]. Building on this foundation, the present work extends the hybrid approach to audio by integrating the Walsh–Hadamard Transform with AES in Galois/Counter Mode (AES- GCM). The approach is format-agnostic, suitable for a wide range of audio formats such as WAV, MP3, and FLAC, and can be enhanced with optional coefficient permutations or selective modifications to increase obfuscation or achieve lightweight compression. By merging these two domains—signal transformation and cryptographic encryption—the hybrid Walsh–AES scheme provides a robust and efficient framework for securing audio content against interception, tampering, and unauthorized reproduction. Note: This work is conducted for experimental purposes. The Walsh–Hadamard Transform (WHT) is added in this study solely to explore its effect on performance metrics, computational load, and data characteristics within a controlled setting. II. WALSH FUNCTIONS AND HADAMARD MATRIX To define the Walsh function, it is necessary to define the Rademacher function [6,7]. Definition 1. The Rademacher system is defined as Integration of Walsh Functions Into Aes-based Audio Encryption Svetlana Grigoryan 1 and Sergo Episkoposian 2 1 Institute of Information and Telecommunication Technologies and Electronics, National Polytechnic University of Armenia, Yerevan, Armenia Email: svetlanagrigoryan65@gmail.com, svetlanagrigoryanmt840@polytechnic.am 2 Faculty of Applied Mathematics and Physics, National Polytechnic University of Armenia, Yerevan, Armenia Email: sergo.episkoposyan@polytechnic.am Abstract: We propose a hybrid audio encryption method combining Walsh–Hadamard transforms with AES- GCM to secure digital recordings. Unlike prior approaches relying solely on cryptography or signal scrambling, our dual-layer scheme ensures waveform obfuscation and strong cryptographic protection. Experiments confirm full-fidelity recovery and broader applicability across formats, improving robustness over recent single-domain techniques. Keyword: Hybrid Audio Encryption, Walsh–Hadamard Transform, AES-GCM, Cryptography, Audio Security.