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Top1. Introduction
Nowadays digital documents are increasing with a terrifying amount, security of these documents by effective techniques are major concern in the field of research from last few decades. So, the digital watermarking is found suitable for copyright protection, owner identification and security etc. Kaur et al. (2020) and Zhang et al. (2016). Watermarking is the method of implanting a single or dual secret information in terms of tag, label or digital signal into an original media Patel et al. (2011). The cover image is embedded with the watermark image in a visible or invisible manner, where secret information is watermark image in Nikolaidis et al. (1998) and Xianghong et al. (2003). There are many research problems in the field of digital watermarking like imperceptibility of watermark, security and robustness which needs to be enhanced in Eyadat et al. (2005) and Liyun et al. (2006). Thus, watermark embed in such a way that quality of original media does not damage and watermark cannot be extracted effortlessly in Liyun et al. (2006) and Xianghong et al. (2003). Further, digital watermarking method can be classified on various categories on the basis of domain, robustness, type of media, recovery process and perceptivity. A simple organization of digital watermarking is shown in fig.1.
Figure 1. Categorization of digital watermarking
According to domain based, watermarking techniques can be divided into two spatial domain or transform domain in Aslantas, (2008) and Loukhaoukha et al. (2014). In spatial domain method embedding can be done by altering the image pixels directly, whereas in transform domain, watermark is embedded by modifying the coefficients of transformed image Rawat et al. (2012) and Su et al. (2013). Spatial domain methods have low computational cost and easy to use rather than transform domain techniques. Least significant bit, spread spectrum and correlation are some common techniques of spread spectrum domain according to Maity et al. (2011). However, transform domain watermarking has discrete cosine transform (DCT), Discrete wavelet transform (DWT), Singular value decomposition (SVD), Quaternion Hadamard Transform (QHT) and many other Santhi et al. (2013). Nowadays researchers are working on watermarking with cryptography for securing the digital media Priya et al. (2018). Modern cryptography follows a strong scientific method and plans cryptographic algorithms, making such algorithms hard to break by an opponent. On the basis of above discussions robust and secure watermarking method for color image using cryptosystem and Arnold transformation is presented. The scheme presented in paper is novel because of following contributions:
- 1.
Here, we present an innovative robust and secure watermarking based on Paillier cryptosystem and Arnold transformation for color image.
- 2.
The requirements of robustness and transparency in digital watermarking approaches are always a trade-off in applications. Robustness of proposed method is increased with better imperceptibility of watermark image.
- 3.
The proposed method is also robust against attacks, such as salt & pepper, filtering, compression and rotation etc.
The remaining work discussed in this manuscript is as literature review used in this paper is described in section 2, preliminaries used in this paper are described in section 3. Proposed algorithm with watermarking process followed by encryption procedure is described in section 4. An analysis section with comparison results is presented in section 5. Finally, the conclusion section is represented in section 6.
Top2. Literature Review
Some important watermarking methods have been proposed in last years by probable researchers are as follows: