A modified approach to data hiding in Microsoft Word documents by change-tracking technique

Abstract

Steganography is a hidden way of communication, where one person communicates with the other by using some medium under the garb of a cover, without any suspicion created on the part of any unauthorized intermediary about the existence of the secret message. Linguistic steganography is about hiding information in natural language text. Synonym substitution is an important transformation used in linguistic steganography. In this paper, we are going to show a method of redesigning the change tracking technique for hiding the secret message in Microsoft Word document to increase the embedding capacity and to decrease the suspicion of any intermediary about the message’s existence. The secret message in bit form is concealed by performing linguistic steganography using synonym substitution method. In conventional change tracking technique for information hiding in Microsoft Word document, the generated Huffman’s codes of rare words are lengthier as compared to common words, leading to more suspicion in the stego-document due to the usage of rare words as compared to common words as synonyms. To overcome this problem, the proposed algorithm is designed in such a way that familiar synonyms are used more often to hide more bits and avoid suspicions. Keywords: Steganography, Change tracking, Huffman coding, Microsoft Word