MULTI-CHANNEL ECG-BASED STEGANOGRAPHY

Abstract

There is a growing tendency for the concealment of secure information into electrocardiogram (ECG) signals in a way that the embedded ECGs still remain diagnosable. The average length of ECG recording for a primary diagnosis takes no longer than 1[Formula: see text]min yielding to limit its concealment capacity. To overcome this drawback, we enhanced both concealment capacity and embedding quality by: (I) using 12-lead ECGs to span more embedding space, (II) shuffling input message bits via nonlinear feedback shift register (NLFSR) method, (III) inserting the selected bits of each channel into the high-frequency wavelet coefficients of non-QRS parts. Inserting the message bits into high frequency coefficients of less important ECG parts leads to preserve the quality watermarked ECGs. To assess the proposed method, a text containing different letters (changes with size of both non-QRS segments and high-frequency sub-band) was hidden through 12-lead ECG signals of 56 randomly selected subjects of PTB database, where each signal length is 10[Formula: see text]s. The performance was compared to state-of-the-art ECG-based steganography schemes in terms of the following criteria: percentage residual difference (PRD), peak signal to noise ratio (PSNR), structural similarity index measure (SSIM) and bit error rate (BER). Our results showed that the proposed scheme has benefits of fast computing along with secure embedding, providing high capacity of data hiding.