Text steganography: a novel character‐level embedding algorithm using font attribute

Abstract

Text Steganography uses text documents as cover medium to communicate the secret messages, covertly, by making unnoticeable distortions in the cover medium. Character-Level Embedding Technique (CLET), a variant of text steganography, embeds a secret character by serially marking/distorting an identical character in the cover medium. Hence, these techniques suffer from low embedding capacity as the occurrence of certain alphabets in a text document is not uniform/guaranteed. In addition, identification of the marked cover character itself can reveal the hidden secret. This makes the CLET a less preferable choice. To overcome the aforementioned shortcomings, this paper proposes a novel CLET by introducing the Frequency Normalization Set in combination with the Character and String Mapping. The combination allows a low occurring character to get embedded in several cover characters, and thereby boosts its embedding probability. In addition, the combination also ensures the uniform embedding probability of secret characters. A font attribute called the character spacing is used to embed the secret. Experiments were conducted to investigate the embedding capacity, uniformity in embedding probability and frequency profile of stego characters of the proposed method. A comparison of the proposed method with the existing CLET algorithms is also provided. Various applications and the security aspects of the proposed method have also been discussed.

A Comparative Analysis of Arabic Text Steganography

“…The algorithm can only be applied to specific languages, hence there is a need to extend its embedded method to be applied in any language. The concept of utilizing the font attributes and character frequency to embed the secret characters was presented by the authors of [56]. To accomplish the uniform appropriation in stego characters with the uniform hiding likelihood, this method integrates four models: Frequency Normalization Set (FNS), Character String Mapping (CSM), embedding, and extracting.…”

Modern Text Hiding, Text Steganalysis, and Applications: A Comparative Analysis

“…In the Unicode, there are special zero-width characters (ZWC) which are employed to provide specific entities such as Zero Width Joiner (ZWJ), e.g., ZWJ joins two supportable characters together in particular languages, POP directional, and Zero Width Non-Joiner (ZWNJ), etc. Practically, the ZWC characters do not have traces, widths or written symbol in digital texts [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 11 , 15 , 18 , 25 , 26 , 27 , 28 , 33 , 34 , 41 , 42 , 43 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 , 60 , 61 , 62 , 63 , 64 , 65 , 66 , 67 , 68 , 86 , 87 , 88 , 89 , 90 , 91 , 92 , 93 , 94 , 95 , 96 , 97 ,…”

“…The feature/format-based methods involve modifying some features of the cover text such as font size, style, color, etc. that could be altered to conceal secret bites [ 18 , 21 , 24 ]. For instance, the dotting feature of the Arabic texts can be used for marking the SM bits by displacing letter points and diacritics [ 116 , 117 , 118 , 119 ].…”

“…to access sensitive information during data transmission. Therefore, demand is growing for intelligence and multimedia security studies that involve not only encryption, but also covert communication whose essence lies in concealing data [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 ]. Recently, information hiding or data hiding in digital texts, known as text hiding, has drawn considerable attention due to its extensive usage, and potential applications in the cybersecurity and network communication industries [ 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 ...…”

“…During the last two decades, many text hiding algorithms have been introduced in terms of text steganography and text watermarking for covert communication [ 1 , 6 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 20 , 31 , 36 , 39 , 51 , 91 ], copyright protection [ 3 , 4 , 5 , 7 , 18 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 44 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 , 60 , 61 , 62 , 63 , 64 , 65 , 66 , 67 , 68 , 72 , 73 , 74 , 75 , 87 , <...>…”