A Review and Comparison for Audio Steganography Techniques Based on Voice over Internet Protocol

Cryptography and steganography are the major role approaches for covert communications. While cryptography enciphers the information in such a way to be non-understandable for unauthorized persons, steganography conceals secure information in ordinary cover data without making perceptible variations in cover data to make data attackers in illusion and they consider the transmitted data is just ordinary data. Therefore, steganography is considered superior compared to cryptography because the encrypted attract the attention of the data attackers. However, it requires bandwidth or saving storage much greater than the hidden secure data. Steganography can be used in different modes such as offline and online, also it can be utilized with different data cover such as image, video, audio, text, and data frames. This study focuses on the most challenging mode in steganography, which is online (i.e. real-time steganography). In addition, it focuses on the most important kind of cover media, audio signals, which should be processed in real-time. Accordingly, this study presents a focused review on data hidden in the Voice over Internet Protocol (VoIP) network where VoIP represents the standard of real-time communication-based on delivery voice over Internet. In addition to a brief survey for the existing real-time steganography approaches, this study also highlights the strengths and weaknesses of each approach. The rubric for assessing the approaches is based on some contradictory requirements for successful steganography approaches. The most important requirements include data embedding rate, imperceptibility, security, robustness, and algorithm complexity which specify the effectiveness of any steganographic system. This study concludes that most of the existing approaches still lacked some features in one or more of the main requirements for real-time security-based steganography.