Enhancement of Text Steganography Technique Using Lempel-Ziv-Welch Algorithm and Two-Letter Word Technique

Abstract

Text steganography is regarded as the most challenging type to hide secret data to a text file because it is not enough unnecessary information compared with other carrier files. This study aimed to deal with the capacity (how much data can be hidden in the cover carrier) and security (the inability of disclosing the data by an unauthorized party) issues of text steganography. Generally, the data hiding capacity of text steganography is limited, and imperceptibility is very poor. Therefore, a new scheme was suggested to improve the two-letter word technique by using the Lempel-Ziv-Welch algorithm. This scheme can hide 4 bits in each position of a two-letter word in the cover text by inserting a nonprinting Unicode symbol. Each two-letter word can have four different locations in the text. Some experiments were conducted on the proposed method (enhancement) and our previous method (two-letter word) to compare their performance applying twelve secret message samples in terms of capacity and Jaro-Winkler. On the other hand, the performance of our proposed method was compared with other related studies in terms of capacity. The results show that the proposed method not only had a high embedding capacity but also reduced the growing size ratio between the original cover and stego cover. In addition, the security of the proposed approach was improved through improving imperceptibility and by using stego-key.