Security of cass data hiding scheme under the scenarios of KMA and WOA

This paper presents a theoretical analysis on the security of CASS (Correlation-and-bit-Aware Spread-Spectrum) data hiding scheme for the first time. By evaluated with the residual entropy of the secret key and the mutual information between the observations and the secret key, the security of CASS is investigated under the scenarios of Known Message Attack and Watermarked Only Attack. In addition, this paper compares data hiding security between CASS and the conventional Additive Spread-Spectrum (Add-SS) data hiding scheme. Theoretical analysis and simulation results show CASS scheme outperforms Add-SS scheme in terms of data hiding security when Document to Watermark Ratio (DWR) is low and performs comparably when DWR is high.