1. Pictures Worth More Than 1000 Words
STEGANOGRAPHY:
Hiding Data in Images
Presented By: Olena Vikariy and Andrew Cavanaugh
Image: Metamorphose II
M.C. Escher

2. What is Steganography?
From the Greek “steganos” meaning covered and “graphy” meaning writing or drawing
The process of hiding information, data, messages, etc. in digital media
Originates from the Greek prisoner, Histiaeus, who tattooed a fellow prisoner’s head with a message and sent to his army.

3. What Kinds of Files can be Used to Hide In?
Most used today:
Images: .bmp, .gif, .jpg/.jpeg
Sound files: .wav
Text files: .txt, .doc
Other: .html, .xml

4. A Few Key Words and Phrases
Cover Image: the image in which the data will be hidden; carrier image, overt or host file
Covert Data: refers to the data that has been hidden in the image
Stego-image, -carrier, -medium: an image that contains hidden data
Steganalysis: the process of detecting and finding data hidden by steganography techniques

5. Steganography Techniques
Most used today:
Image Domain: Least Significant Bit (LSB) - substitution based; the 1st or 2nd LSB are changed; visually identical to original image; 24-bit images provide better cover than an 8-bit image
Transform Domain: spreads the data throughout the image and performs a second layer transform; Discrete Cosine Transform (DCT) used by JPEGs

6. How is Steganography Applied?
Covert Information Transfer (i.e. Spy stuff, Government communication)
Copyright Protection: digital watermarking
Convenient storage and transmission of multiple media
Future Possibility: use in holograms on credit cards as a means of identification; currently very expensive to produce

7. Some Useful References:
Various Papers on Steganography:
List of various steganographic tools: (most free and some commercial)
Book: Hiding in Plain Sight: Steganography and the Art of Covert Communication by Eric Cole