State-of-the-Art in Techniques of Text Digital Watermarking: Challenges and Limitations

Abstract

Data protection from malicious attacks and misuse has become a crucial issue. Various types of data, including images, videos, audio and text documents, have given cause for the development of different methods for their protection. Cryptography, digital signatures and steganography are the most well known technologies used to protect data. During the last decade, digital watermarking technology has also been utilized as an alternative to prevent media forgery and tampering or falsification to ensure both copyright and authentication. Much work has been done to protect images, videos and audio but only a few algorithms have been considered for text document protection with digital watermarking. However, our survey observed that available text watermarking algorithms are neither robust nor imperceptible and as such remain unsecured methods of protection. Hence, research to improve the performance of text watermarking algorithms is required. This paper reviews current watermarking algorithms for text documents and categorizes text watermarking methods based on the way the text was treated during the watermarking process. It also discusses merits and demerits of available methods as well as recent proposed methods for evaluating text watermarking systems and the need for further research on digital text watermarking.

A Comparative Analysis of Information Hiding Techniques for Copyright Protection of Text Documents

“…In the second stage, the watermark string is converted to a binary string, which is modified by a hash function according to an optional key, and then an invisible watermark string is generated for embedding it into special locations in the cover text. Finally, it is inserted into special locations where the watermark string will not be affected by attacks [2,4,6,7].…”

“…Two different terms are used for this phase, that is, extraction and detection. Although authors often regarded both as similar functions in some literature, we can distinguish them in this way: whereas the extraction discovers the watermark string from the watermarked document and authenticates its integrity, the watermark detection verifies the existence of the watermark string from the watermarked text [4,6,7,48]. [11, 28-32, 52, 53].…”

“…In other words, text is an important part of communication between people compared to other media. Secondly, text watermarking has no clear evaluation criteria to analyze its efficiency [6][7][8][9][10].…”

“…The cryptography and information hiding are security systems that are used to protect data from deceivers, crackers, hackers, and spies. Commonly, most of the malicious users want to leave traces from cuts, manipulations, and infections [7]. The cryptography scrambles a plain text into ciphertext which is reversible without data loss.…”

“…Watermarking is concerned with hiding a small data in digital files such that the hidden data is robust to alterations and adjustments. In other words, watermarking aims to protect intellectual property of digital media against unauthorized copy or access by embedding a watermark (visible or invisible) in the cove media which can remain beside the data, and it can be used whenever there is any query about the originality of media (e.g., the hidden watermark refers to the original owner) [2][3][4][5][6][7][8][9][10]. Over the last two decades, many information hiding techniques have been proposed in terms of text watermarking and text steganography for copyright protection [11][12][13][14], proof of ownership [15][16][17][18][19][20][21][22][23], and copy control and authentication [24][25][26][27][28][29][30][31].…”