Con(dif)fused voice to convey secret: a dual-domain approach

Owing to the rapid development and advancements in the field of networks and communication, sharing of multimedia contents over insecure networks has become vital. The confidentiality of audio signals is predominantly needed in military and intelligence bureau applications. The proposed algorithm addresses this issue by encrypting audio signal using chaotic maps in spatial and transform domain. Discrete Fourier transform (DFT), discrete cosine transform (DCT) and integer wavelet transform (IWT) approaches are considered for the experiment. The algorithm involves three-layer security of confusion and diffusion in the spatial domain, and confusion in the transform domain. The confusion in the transform domain is equivalent to diffusion in the spatial domain. Different sizes of audio samples are considered to validate the effectiveness of the proposed scheme. Experimental results prove that the DFT-assisted encryption scheme is more efficient than the DCT- and IWT-based methods because the DFT scheme employs effective diffusion through reversible phase coding. Effectiveness of the proposed method is substantiated using various metrics. Correlation coefficients arrive significantly closer to zero; number of samples changes rate (NSCR) value is at 100% and scrambling degree close to 1. Besides, the proposed scheme has a larger keyspace higher than 2¹²⁸. Thus, the proposed algorithm has the potency to withstand the statistical, differential and brute force attacks.