Robust and secure zero-watermarking algorithm for color images based on majority voting pattern and hyper-chaotic encryption

Robust zero-watermarking is an effective and distortion-free technique for copyright protection and has become a research hotspot in the field of digital watermarking. In the face of weak robustness and security of existing schemes, this paper presents a novel robust and secure color image zero-watermarking algorithm based on majority voting pattern and hyper-chaotic encryption. In the proposed algorithm, firstly an original color image is decomposed by one-level discrete wavelet transform (DWT) and the corresponding low-frequency components of three channels are partitioned into blocks. Then, to resist strong attacks, we construct a distinguishable robust binary feature matrix extracted from all blocks and color components by using a combination of Frobenius norm in the singular value decomposition (SVD) domain and majority voting pattern. To promote security, a binary copyright logo is confused and diffused by hyper-chaotic Lorenz system. Finally, it performs a bitwise exclusive-or operation on the binary feature matrix and the encrypted copyrighted logo to obtain a zero-watermark signal. Experimental results indicate that in addition to the high-level security, the proposed zero-watermarking algorithm also has a stronger robustness against common geometric and non-geometric attacks, including rotation, scaling, filtering, JPEG compression and noise addition, compared with some existing typical zero-watermarking and traditional watermarking methods.