Mohd Rosmadi Mokhtar

High capacity, transparent and secure audio steganography model based on fractal coding and chaotic map in temporal domain

Information hiding researchers have been exploring techniques to improve the security of transmitting sensitive data through an unsecured channel. This paper proposes an audio steganography model for secure audio transmission during communication based on fractal coding and a chaotic least significant bit or also known as HASFC. This model contributes to enhancing the hiding capacity and preserving the statistical transparency and security. The HASFC model manages to embed secret audio into a cover audio with the same size. In order to achieve this result, fractal coding is adopted which produces high compression ratio with the acceptable reconstructed signal. The chaotic map is used to randomly select the cover samples for embedding and its initial parameters are utilized as a secret key to enhancing the security of the proposed model. Unlike the existing audio steganography schemes, The HASFC model outperforms related studies by improving the hiding capacity up to 30% and maintaining the transparency of stego audio with average values of SNR at 70.4, PRD at 0.0002 and SDG at 4.7. Moreover, the model also shows resistance against brute-force attack and statistical analysis.

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

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.