Seyyed Mohammad Reza Hashemi - Young Researchers and Elite Club Islamic Azad University Qazvin, Iran
Mohammad Mahdi Deramgozin - Department of Electrical, Computer and Information Technology Islamic Azad University, Qazvin Branch, Iran
M Hajighorbani - Department of Computer Engineering, Iran University of Science and Technology, Tehran, Iran
B Minaei-Bidgoli - Department of Computer Engineering, Iran University of Science and Technology, Tehran, Iran

Since the beginning of digitization of natural and legal documents, owners of documents are always looking for a good way to protect copyright. Due to the large volume of text information in today's world and sharing them on the Internet there is the need to do research in this field and encryption and steganography of digital documents as a secret technique in digital texts, can be of great use. An issue that is seriously considered today is preventing forgery of electronic documents and applying copyright in a hidden way in document. In this article, we examine five watermarking methods for digital texts including: point insertion method, change the shape of the letters, and insert stretch characters between characters of the words, the developed method of inserting stretch characters between characters of the words and the improved لا method. Methods mentioned are thoroughly explained

Information Hiding, Copyright, Watermarking, Steganography