I think we’re all guilty of drawing up the plans in our heads, with the thermite charge on your hard drive and the big red panic button. But all of these plans essentially have the problem of having to detect a breach of security. An interested party need only be just as creative to detect and thwart your carefully laid booby trap. Nothing quite says "I contain incriminating information" like a booby-trapped PC.
There are some classical methods of hiding communication in plain sight using pre-arranged coded speech an writing patterns which at first look appear as mundane however in actuality the people as saying something completely different. The Russian black market and crime syndicates developed a language using certain chess movements. Prison detainees used vulcanized rubber and crude utensils to draw elaborate tattoo’s denoting rank and other qualities.
By itself stegnagraphy is only good for covert communications to one or more parties. Much has been said about the presence of stegnagraphy laced content in news groups and other public content. Granted the amount of actual covert communications is very exaggerated. The difficulty in using stegnagraphy is that many stegnagraphy techniques can be scanned for just like you would scan for a virus or malware. The very presence of a stegnagraphic utility on your computer or some one accessing a known security website or downloading a known utility can raise a flag to a security analyst that covert communication is likely occurring.
When addressing the topic of including stegnagraphy into freenet (an open source anonymous network) "...Steganography is an ongoing battle of attrition, obscurity and constantly updating are sadly the best defenses in it. Again it's down to `better
the way we do it than the way you don't...' " Basically, the same defenses that viruses use to avoid detection are the only strengths that stegnagraphy by itself has. Another strength it has is that it is not part of the popular user-land security dogma which states that firewall + anti virus + anti spy ware == secure. (which is like saying that its okay not to wear a seat belt in a car because your wearing a condom). So it is only effective against passive detection but thats about it.
-=- TABLE OF CONTENTS -=-
x .......... Introduction
1 .......... Use and purpose
2 .......... Mediums and How it works
3 .......... Utilities currently available
A .......... Works Cited
1 .......... Use and purpose
Covert communication is where bandwidth is stolen from a legitimate communication to create a secret channel of communication. So the purpose of stegnagraphy is to create a parasitic hidden communication, carried by a legitimate communication. This is done so that communication can be made in a public space with out drawing attention to it self.
A person who would want to make use of this would be a human rights violation observer who is passing information to an international human rights advocacy group like Amnesty International or the UN. The local authorities would very likely be suppressing information of that sort. If the local authorities would catch a communication a report on an incident, its very likely the reporter would be silenced in one way or another.
In the US we enjoy freedom of speech, these rights are being whittled away at under the guise of national security. In other countries, un-censored speech has dire and deadly consequences. Just because what I write may be unpopular, that is not a valid excuse for killing or torturing me. Yet untold numbers of people suffer those consequences daily just because they say something not deemed acceptable by their locality/nation/culture. Development of covert communications and cryptography may seem trivial to us now, but development of these tools can save lives. Allowing the public the use of these tools may have serious consequences for law enforcement, but criminalizing their use and possession has vast and horrible consequences for us as society.
2 .......... Mediums and How it works
A good example is a chess game, in the previous example of criminal elements use of coded speech and mannerisms, a chess game is interpreted in a different game, certain reactions to moves are communications, the moves are all valid moves, only their context has changed. This is a high bandwidth covert channel, it uses a lot of the bandwidth of the communication. High bandwidth is where the legitimate communication itself is placed into a different context and interpreted to mean something else. If one of the players affixed a microdot containing private information and affixed it on to the other players chess board then this would be low bandwidth.
The Trusted Computer Security Evaluation Criteria (aka TCSEC) is a set of criteria established by the National Computer Security Center which is managed by the NSA. According to TCSEC there are two types of covert communications. The first is a storage channel, which modifies a stored object into something else less sensitive. The second is a timing channel which manipulates the timing in a communication to transmit the sensitive information.
An example of the two is Jsteg and tcp/ip timing. Jsteg hides information in an existing jpeg in the formatting of the picture which does not significantly change the original picture. Tcp/IP timing is where a normal mundane tcpip request is carried out but it is delayed in a pre-determined fashion which the timing of the transmition of the packets is the medium of communication. A less technical example would be the chess example where the microdot would be the storage channel and the timing of chess movements would be the timing channel.
Another example of using a parasitic medium is communicating using stegnagraphy using what is called chaffing and winnowing. This sends out multiple hidden communications using a secondary channel to provide a key to identify which communication is correct. This method utilizes the previous forms and adds in a code which authenticates the communication.
Lastly, the weakness of stegnagraphy is that it relies on constant change to maintain the communications secrecy. Companies like SARC are using watermarking technologies which are similar to anti-virus technologies to detect both stegnagraphic content and utilities, it is vital that cryptography be used in order to maintain the secrecy of the information within the hidden communication.
3 .......... Utilities currently available
From Wikipedia (http://en.wikipedia.org/wiki/Steganography#Implementations)
Online (Hiding text)
* mozaiq Has a large library of stock photos it provides if you can't supply a photo of your own. A good starting point for creating simple steganographic examples.
* spammimic.com will take a sentence that you provide and turn it into text that looks to all the world like spam.
* Hide text in a PNG or BMP image and its corresponding decoder.
** Online (Hiding files)
* Stegger, PHP Steganography—PHPClasses Repository—An open source, feature rich, secure implementation of image steganography written in PHP.
** Downloadable (Hiding text)
* Concealar ...coz a picture speaks a thousand words! The software "Concealar" hides text into images & pictures by a password using cryptographic and steganographic techniques. Encryption algorithm used for text is AES (Rijndael) and the password is hashed with SHA512. The software don't create any noise in the resultant image so pattern-finding & pixel-mapping techniques of steganalysis don't work on this software.
* Bapuli Online—implementing steganography using Visual Basic.
* BitCrypt BitCrypt is one of the easiest to use encryption tools which at the same time provide ultra-strong encryption. It uses up to 8192 long bit key ciphers to encrypt the text, and then stores the encrypted text within bitmap images.
** Downloadable (Hiding files)
* Hiding Glyph: Bytewise Image Steganography: Hides any file (or folder) into any losslessly compressed image (BMP, PNG, etc…). (freeware)
* BestCrypt Commercial Windows/Linux disk encryption software that supports hiding one encrypted volume inside another
* Crypto-Stego Utility for the Zillions of Games program.
* Digital Invisible Ink Toolkit An open-source cross-platform image steganography suite that includes both steganography and steganalysis implementations.
* FreeOTFE Free, open-source Windows/PocketPC/Linux disk encryption software that supports hiding one encrypted volume inside another, without leaving any evidence that the second encrypted volume exists. This probably resists any statistical analysis (as opposed to tools that conceal data within images or sound files, which is relatively easy to detect).
* MP3 Steganographic File System, a description of an approach to create a file system which is implemeted over MP3 files.
* OutGuess A steganography application to find data in Jpeg images.
* PCopy A steganography commandline tool with a userfriendly wizard which can produce lossless images like PNG and BMP. Special features are RLE, Huffman compression, strong XOR encryption and the Hive archiving format which enables the injection of entire directories.
* Phonebook FS protects your disks with Deniable Encryption
* RevelationA platform independent tool created in Java that can hide any data file within a 24-bit bitmap image. Features a unique wizard style interface in the encoding and decoding process.
* stego and winstego Steganography by justified plain text.
* Stego-0.5, a GNOME/GTK+ based GUI for LSB algorithm. License (GPL)
* Stego Archive Source for a large variety of steganography software.
* Steghide Free .jpeg and .wav encryption for Linux and other operating systems.
* SteGUI Free GUI for Steghide for Linux.
* TrueCrypt Free, open-source Windows/Linux disk encryption software that supports hiding one encrypted volume inside another, without leaving any evidence that the second encrypted volume exists. This probably resists any statistical analysis (as opposed to tools that conceal data within images or sound files, which is relatively easy to detect).
* Peter Wayner's website—sample implementations of steganographic techniques, by the author of Disappearing Cryptography.
* NetTools Steganography by hiding data in pictures, archives, sounds, text files, html, and lists.
* Qtech Hide & View v.01 is the newest BPCS-Steganography program for Windows. This is an image steganography. (Free to use)
* ZebDisk ZebDisk is a free software, and you can store, and share your files on the internet with it using Google’s Picasa service.
* SteganoG a simple program to hide a text file in a .bmp file.
(Wikipedia, on Implemenataions of Stegnagraphy, Dec 2007)
We also mentioned Jsteg which can be found at "http://www.theargon.com/achilles/steganography/jpeg-steg/"
A. .......... Works cited
Sarc Website. Accessed March 2007
Toad "Attacks and weaknesses." Accessed March 2007
Engle, Sophie. (Viewed March 2007). "CURRENT STATE OF STEGANOGRAPHY:
USES, LIMITS, & IMPLICATIONS"
Wikipedia.org (Accessed March 2007). "Steganography"
Wikipedia.org (Accessed March 2007). "Covert Channel"
Wikipedia.com (Accessed March 2007). "Russian Criminal Tatoos."
http://www.theargon.com/ (Accessed December 2007). "theargon stegnagraphy web archives."