Editing Steganography (section)

{{short description|Hiding messages in other messages}}
{{Use dmy dates|date=November 2023}}
{{for-multi|the process of writing in shorthand|Stenography|the prefix "Stego-" as used in taxonomy|List of commonly used taxonomic affixes}}
[[File:Steganography.png|upright=1.4|thumb|The same image viewed by white, blue, green, and red lights reveals different hidden numbers.]]

'''Steganography''' ({{IPAc-en|audio=en-us-steganography.ogg|ˌ|s|t|ɛ|ɡ|ə|ˈ|n|ɒ|ɡ|r|ə|f|i}} {{respell|STEG|ə|NOG|rə-fee}}) is the practice of representing information within another message or physical object, in such a manner that the presence of the concealed information would not be evident to an unsuspecting person's examination. In computing/electronic contexts, a [[computer file]], message, image, or video is concealed within another file, message, image, or video. Generally, the hidden messages appear to be (or to be part of) something else: images, articles, shopping lists, or some other cover text. For example, the hidden message may be in [[invisible ink]] between the visible lines of a private letter. 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]].<ref name=stegokey>{{cite journal|last=Fridrich|first=Jessica|author2=M. Goljan|author3=D. Soukal|title=Searching for the Stego Key|journal=Proc. SPIE, Electronic Imaging, Security, Steganography, and Watermarking of Multimedia Contents VI|year=2004|volume=5306|pages=70–82|url=http://www.ws.binghamton.edu/fridrich/Research/Keysearch_SPIE.pdf|access-date=23 January 2014|doi=10.1117/12.521353|series=Security, Steganography, and Watermarking of Multimedia Contents VI|bibcode=2004SPIE.5306...70F|s2cid=6773772|editor1-last=Delp Iii|editor1-first=Edward J|editor2-last=Wong|editor2-first=Ping W}}</ref>

The word ''steganography'' comes from [[Greek language|Greek]] ''steganographia'', which combines the words ''steganós'' ({{Wikt-lang|el|στεγανός}}), meaning "covered or concealed", and ''-graphia'' ({{Wikt-lang|el|γραφή}}) meaning "writing".<ref>{{Cite web|url=https://www.merriam-webster.com/dictionary/steganography|title=Definition of STEGANOGRAPHY|website=Merriam-webster.com|access-date=14 December 2021}}</ref> 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. 

The advantage of steganography over cryptography alone is that the intended secret message does not attract attention to itself as an object of scrutiny. Plainly visible [[encrypted]] messages, no matter how unbreakable they are, arouse interest and may in themselves be incriminating in countries in which encryption is illegal.<ref>{{cite web|url=http://www.alternet.org/story/11986/|title=Confounding Carnivore: How to Protect Your Online Privacy|publisher=[[AlterNet]]|archive-url=https://web.archive.org/web/20070716093719/http://www.alternet.org/story/11986/|archive-date=16 July 2007|access-date=2 September 2008|last=Pahati|first=OJ|date=29 November 2001}}</ref> Whereas cryptography is the practice of protecting the contents of a message alone, steganography is concerned with concealing both the fact that a secret message is being sent and its contents.

Steganography includes the concealment of information within computer files. In digital steganography, electronic communications may include steganographic coding inside a transport layer, such as a document file, image file, program, or protocol. Media files are ideal for steganographic transmission because of their large size. 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. The change is so subtle that someone who is not looking for it is unlikely to notice the change.