What is steganography?

What is steganography?

• What is steganography?

• Regarding cryptography

• Classifications of steganography

• Who uses steganography?

Steganography comes from the Latin & Greek roots:

• Steganography comes from the Latin & Greek roots:

• Steganos (Greek) meaning covered
• Graphy (Latin) meaning writing or drawing
• Steganography is the science of hiding information. (Kessler)
• Steganography is the art of concealing the existence of information within seemingly innocuous carriers (Johnson)

• The Art & Science of using overt objects to create and exploit covert communications. (Trawick)

Definitions

• Definitions

• NSA: Definition 4 - Covert channels are those that "use entities not normally viewed as data objects to transfer information from one subject to another.“
• RSA Labs: A covert channel enables the prisoners [actors] to exchange secret information through messages that appear to be innocuous.
• Wikipedia: a covert channel is a type of computer security attack that creates a capability to transfer information objects between processes that are not supposed to be allowed to communicate by the computer security policy.

• Steganography is arguably the most common covert channel used (but only among those who consider steganography a covert channel)

Steganography and Cryptography are not the same

• Steganography and Cryptography are not the same

• Cryptography seeks to scramble the contents of a message in such a way that it is unreadable without the proper key
• Steganography seeks to completely hide the existence of the message

• The two concepts can be used together

• Order of operations is relevant
• A hidden message that is encrypted
• An encrypted message that has a hidden message inside

Insertion

• Insertion

• Substitution

• Generation

Adds to beginning or ending of file

• Adds to beginning or ending of file

• In between BOF and EOF headers

• Practically unlimited storage

• Does not affect the appearance of original

• Does not modify the original data

• Metadata for the file may be changed, however

• File size changes proportionately

Changes existing data in the original file

• Changes existing data in the original file

• In images change typically applied to Least Significant Bit (LSB)

• Limits to how much you can hide

• Can change the visual appearance

Uses an algorithm and a hidden file to generate a new file

• Uses an algorithm and a hidden file to generate a new file

• Unlimited storage

• Generates pictures such as fractals, static or noise depending on algorithm used.

• Use may allow steganography image to remain intact even after processing such as format change

Terrorists are thought to use steganography (particularly Web Images) to transmit messages to communicate and coordinate criminal activity

• Terrorists are thought to use steganography (particularly Web Images) to transmit messages to communicate and coordinate criminal activity

• Commercial & Government users use it to communicate with employees and hide critical data

• Use as a Dead-Drop so parties don’t know each other

Try to open all the pictures?

• Try to open all the pictures?

• File in question is usually password protected
• George Trawick’s PhD Dissertation
• Looking for traces of Steganography, something which narrow down the pool of possibilities
• In the example of JPEG compression, certain elements remain stable and therefore traceable so that law enforcement can more easier cope with image-altering steganographic techniques

StegDetect

• StegDetect

• Outguess

• Camouflage

• iSteg - http://www.hanynet.com/isteg/index.html

• Pict Encrypt

Uses linear discriminant analysis

• Uses linear discriminant analysis

What is steganography?

• What is steganography?

• Regarding cryptography

• Classifications of steganography

• Who uses steganography?

“Principles of Steganography,” Max Weiss. http://www.math.ucsd.edu/~crypto/Projects/MaxWeiss/steganography.pdf

• “Principles of Steganography,” Max Weiss. http://www.math.ucsd.edu/~crypto/Projects/MaxWeiss/steganography.pdf

• Wikipedia: http://en.wikipedia.org/wiki/Steganography

• Outguess, “Steganography Detection with Stegdetect,” Neil Provos, 1999-2004. http://www.outguess.org/detection.php