Secure fragile watermarking based on Huffman encoding and optimal embedding strategy

Image watermarking is one of the most popular techniques used to assure information security, integrity, and authenticity. Watermarking algorithms can be categorised, according to the domain of insertion, as either spatial or spectral domain-based watermarking approaches. The resulted watermark can also be classified as either strong designed to withstand malicious attacks or fragile designed to detect every possible alteration. In order to combine the advantages of the two categories of watermarking algorithms, this paper proposes a new fragile hybrid domain-based watermarking scheme to get both robustness and imperceptibility using an optimal embedding strategy according to the entropy values of the host images blocs. To enhance security and safety, the watermark undergoes an encryption using Huffman encoding to produce a scrambled watermark. This scheme is evaluated based on different metrics like the peak signal to noise ratio, the structural index similarity, and the normalized correlation coefficient, satisfactory results are attained. The experimental results show that Huffman encryption and optimal blocs selection offer good features of security and imperceptibility.