Textual steganography approaches conceal data in a text cover. ese approaches can be categorized as follows.
is is a nonlinguistic steganography technique that hides data by exploiting the format of text . TFM modifies an original text by employing spaces, misspellings, fonts, font size, font style, colors, and non-color (as invisible ink) to embed an encoded message. However, comparing the original text to the modified text triggers suspicion and enables an adversary to detect where a message is hidden. In addition, TFM can be distorted and may be discerned by human eyes or detected by a computer [25,37].