Steganography

[1] The first recorded use of the term was in 1499 by Johannes Trithemius in his Steganographia, a treatise on cryptography and steganography, disguised as a book on magic.

Some implementations of steganography that lack a formal shared secret are forms of security through obscurity, while key-dependent steganographic schemes try to adhere to Kerckhoffs's principle.

For example, a sender might start with an innocuous image file and adjust the color of every hundredth pixel to correspond to a letter in the alphabet.

Additionally, Demaratus sent a warning about a forthcoming attack to Greece by writing it directly on the wooden backing of a wax tablet before applying its beeswax surface.

In his work Polygraphiae, Johannes Trithemius developed his so-called "Ave-Maria-Cipher" that can hide information in a Latin praise of God.

"Auctor Sapientissimus Conseruans Angelica Deferat Nobis Charitas Potentissimi Creatoris" for example contains the concealed word VICIPEDIA.

[8][9] Examples include: Since the dawn of computers, techniques have been developed to embed messages in digital cover mediums.

In 2003, Giannoula et al. developed a data hiding technique leading to compressed forms of source video signals on a frame-by-frame basis.

[13] In 2008, Yongfeng Huang and Shanyu Tang presented a novel approach to information hiding in low bit-rate VoIP speech stream, and their published work on steganography is the first-ever effort to improve the codebook partition by using Graph theory along with Quantization Index Modulation in low bit-rate streaming media.

[14] In 2011 and 2012, Yongfeng Huang and Shanyu Tang devised new steganographic algorithms that use codec parameters as cover object to realise real-time covert VoIP steganography.

The main idea of their paper is to enhance audio signal reconstruction by fusing steganography, halftoning (dithering), and state-of-the-art shallow and deep learning methods (e.g., RF, LSTM).

Adaptive steganography is a technique for concealing information within digital media by tailoring the embedding process to the specific features of the cover medium.

[19] Their method develops a skin tone detection algorithm, capable of identifying facial features, which is then applied to adaptive steganography.

By incorporating face rotation into their approach, the technique aims to enhance its adaptivity to conceal information in a manner that is both less detectable and more robust across various facial orientations within images.

Academic work since 2012 demonstrated the feasibility of steganography for cyber-physical systems (CPS)/the Internet of Things (IoT).

For example, the letter size, spacing, typeface, or other characteristics of a cover text can be manipulated to carry the hidden message.

[22] Although not classic steganography, some types of modern color laser printers integrate the model, serial number, and timestamps on each printout for traceability reasons using a dot-matrix code made of small, yellow dots not recognizable to the naked eye — see printer steganography for details.

[30] In 2005, Steven J. Murdoch and Stephen Lewis contributed a chapter entitled "Embedding Covert Channels into TCP/IP" in the "Information Hiding" book published by Springer.

[32] Contrary to typical steganographic methods that use digital media (images, audio and video files) to hide data, network steganography uses communication protocols' control elements and their intrinsic functionality.

Such modification can be applied to the protocol data unit (PDU),[34][35][36] to the time relations between the exchanged PDUs,[37] or both (hybrid methods).

The carrier is the signal, stream, or data file that hides the payload, which differs from the channel, which typically means the type of input, such as a JPEG image.

Three prototype papers (Sensicoat, Anilith, and Coatalith) were used to manufacture postcards and stationery provided to German prisoners of war in the US and Canada.

For example, to detect information being moved through the graphics on a website, an analyst can maintain known clean copies of the materials and then compare them against the current contents of the site.

A steganography tool can be used to camouflage the secret message in the least significant bits but it can introduce a random area that is too perfect.

The term Stegware was first introduced in 2017[45] to describe any malicious operation involving steganography as a vehicle to conceal an attack.

In addition, lossy compression schemes (such as JPEG) always introduce some error to the decompressed data, and it is possible to exploit that for steganographic use, as well.

Zheng had allegedly used steganography to exfiltrate 20,000 documents from General Electric to Tianyi Aviation Technology Co. in Nanjing, China, a company the FBI accused him of starting with backing from the Chinese government.

[54] It is possible to steganographically hide computer malware into digital images, videos, audio and various other files in order to evade detection by antivirus software.

This is done through content disarm and reconstruction (CDR) software, and it involves reprocessing the entire file or removing parts from it.

There is the possibility of cataloging these algorithms based on the information held by the stegoanalyst in terms of clear and encrypted messages.