December 4, 2007

Steganography

By: Brittany Bugg and Makenzie Young

What is Steganography?

The art of writing in codeHiding information by embedding messages

within other messagesOnly the person receiving the message can

decode it, but they have to have to the proper code or software to do so.

Background

Dates back as early as Ancient Rome where they would inscribe messages on stone tablets and then pour wax over itThe wax would be scraped off to read the messageMostly used for military intelligenceAnother method used in ancient Greece, tattooing a

message on someone’s head and then allowing their hair to grow back then the receiver of the message would shave their head

Chinese used messengers on foot where they would hide messages on silk cased in wax and the messengers sometimes carried it in them

Applications for Steganography

Hide and Seek (versions 4.1 and 5.0) By Colin Maroney Images 320x480 Spreads data throughtout the GIF in a random fashion

StegoDos Also known as Black Wolf’s Picture Encoder Public Domain software by an anonymous person Works with images that are 320x200 with 256 colors

Steganos is a LSB embedding system that embeds data into images

SecurEngine, an application in which small text files are hidden in larger text files

White Noise By Ray Arachelian

White Noise Example

White Noise was the first software tested that could embed this message (to the left) into the picture above.

Other Examples

Invisible Ink Can be used in documents or even clothing

FingerprintingPeers communicating

Doesn’t stop the fact that there is a message being sent between the peers, which can obviously be detected

Chaffing and winnowingWhere the recipient receives multiple messages where

they can identify the true meaning, but only one of the messages is authentic and the rest are bogus

MicrodotsWhere only a microscope can read the message

Pros

Used for:Watermaking images for copyright protection

Example: holding a $20 bill up to the light and seeing a watermark

Hidden in images, video files, and audio filesConfidentiality of valuable information to

prevent theft

Cons

Unfortunately, steganography can also be used for illegal purposes:Concealing a plan for terroristic threats

It is believed that al-Qaeda used steganographic software to communicate plans with each other before the 9-11 attacks, this has not yet been confirmed

This is a huge threat to the gorvernment

Hiding harmful files Stealing data

http://youtube.com/watch?v=ySkhnqdptzs

Steganalysis

Steganalysis is a way to defeat steganographyStegdetect is a tool used for detecting the content in

images. The only con to steganalysis is that steganography

cannot always be detectedTechniques on attack approach is important

depending on what information is available: Steg-only attack: steganographic medium is available Known-carrier attack: the original cover and the medium are available Known message attack: when the hidden message is known Chosen message attack: when the steganalyst knows the message and has

access to the steganography tool and can embed and analyze messages

Applications for Steganalysis

EnCase, by Guidance Software Inc.

Ilook Investigator, by Electronic Crimes Program

This is an example of a file without embedded text

This is an example of a file with embedded text

Algorithms

Are step-by-step procedures in solving a problem

It is used by steganalysts in decoding messages from images where the focus is right now

Compare/contrast

Stenographydefined by dictionary.com, is “a person who

specializes in taking dictation in shorthand”

Cryptographytransforming information into an unreadable format

Digital WatermarkingWhen an image is embedded with copyright

information

Stenography

A stenographer should not be confused for a steganographer because they do not conceal messages they write in shorthand coding

For example, court reporters They use stenotype machines to type up what the people are

saying Type in codes, some reporters actually have a dictionary of

codes that consist of common words, phrases, etc. Type up to 300 words per minute, the average is 230 In heated court cases up to 250 words can be said

Cryptography

Cryptography is transforming information into an unreadable format

It is used to protect information such as credit card information, email messages, etc.

Unlike steganography, you can tell a message has been encrypted, but in order to decode it you need to have the proper key

Cryptanalysis is the code breaking method

Digital Watermarking

Digital watermarking is a pattern of bits inserted into a picture or file to identify the copyright information.

Like steganography, it is meant to be invisibleThe bits within the image have to be scattered so

that they cannot be tampered with or identifiedThe actual watermark also has to be robust

enough so that if the image is changed, the watermark is still there.

Examples

Sources

http://www.securityfocus.com/infocus/1684http://www.braingle.com/brainteasers/codes/

steganography.phphttp://www.outguess.org/detection.phphttp://palisade.plynt.com/issues/2005May/steganalysis/http://www.strangehorizons.com/2001/20011008/

steganography.shtmlhttp://www.webopedia.com/TERM/C/cryptography.htmlhttp://www.jjtc.com/stegdoc/index2.html