A High Capacity Text Steganography Utilizing Unicode Zero-Width Characters

Information hiding based on text has become the hottest and most discussed aspect of steganography in recent years, because it eases communication and consumes less memory compared to other types. The lack of redundant information in a text file makes it difficult to hide secret bits into a carrier message (CM) without being noticeable. Therefore, the total amount of hidden bits embeddable in a CM contributes immensely to the system efficiency. Today, individuals share information online with the fear that it could be destroyed by third parties. To achieve a structured text hiding system with high embedding capacity, imperceptibility, robustness and high security concurrently, securing sensitive data through encryption is not enough because attackers are able to suspect that a communication channel exist between the sender and the receiver. Therefore, this paper combines both steganography and cryptography to protect our shared information and to achieve a strong and highly secured non understandable text hiding system. We proposed a method which uses pairs of Zero Width Characters (ZWC) to represent each 4-bit binary classification which provides a high embedding capacity and reduces computational complexity than previous methods. The embedding is done by placing the invisible strings of the secret message (SM) into a single position of the open spaces in the CM which provides high invisibility compared to the reviewed methods. One Time Pad (OTP) and XOR bitwise encryption is used to encrypt the inverted message before the embedding process which provides end-to-end security to the system. The experiment shows that the proposed method provides a very high embedding capacity and high robustness than other literature reviewed.