Secure Image & Audio Steganography Using AES-256 Encryption and Hybrid DWT-SVD Frequency Domain Embedding

Abstract: This paper presents a robust dual-layer secure image steganography framework that integrates AES-256 encryption in Counter (CTR) mode with a hybrid Discrete Wavelet Transform and Singular Value Decomposition (DWT- SVD) technique for covert communication. Unlike fragile spatial-domain methods such as Least Significant Bit (LSB) substitution, the proposed system operates entirely within the frequency domain by first encrypting the secret image using AES-256 with SHA-256 key derivation, and then embedding the resulting ciphertext into the high-frequency sub-bands of the cover image's luminance (Y) channel in the YCbCr colour space. Experimental evaluation demonstrates a Peak Signal-to-Noise Ratio (PSNR) of 55.58 dB between cover and stego images, a Structural Similarity Index (SSIM) of 0.99998, a Mean Squared Error (MSE) of 0.1797, and 100% Bit Correct Recovery (BCR) under ideal conditions. The system is delivered as three complementary user interfaces: a Tkinter desktop GUI, a Streamlit web dashboard, and a command-line interface (CLI). An additional audio steganography module extends the same AES-CTR pipeline to WAV files via LSB embedding, demonstrating the modularity of the design. The work addresses key gaps identified in the existing literature, namely the absence of a combined cryptographic and frequency-domain embedding approach, and establishes a publicly benchmarked baseline for future research into error-correcting codes, adaptive alpha tuning, and deep learning steganalysis resistance.

Keywords: Steganography, AES-256, DWT-SVD, Frequency-Domain Embedding, Image Security, PSNR, SSIM, Covert Communication, YCbCr, Cryptography.