1. Steganograp hy By : Uday Deep Singh (IT-2 / 7 th Sem) “The Art Of Hiding Content In Images” 1

2. Discussion What steganography essentially is ? How it works ? Feasibility and constraints. Present day implementations. Steganograph y 2

3. What is it ? Practice of hiding private or sensitive information within something that appears ordinary. Name derived from greek words “steganos” meaning “cover” “graphia” meaning “writing” Lesser known elder brother of cryptography Steganograph y 3

4. Basic terms Carrier/ Cover File – File which has hidden information inside of it. Steganalysis – Process of detecting hidden information inside of a file. Redundant Bits – Information that can be expended Payload – Information which is to be concealed. Steganograph y 4

5. Steganography Carrier files bmp jpeg gif wav mp3 mpeg Amongst others… Steganograph y 5

6. Basic Model of Steganography Steganograph y 6 Encoder Decoder Cover Image Secret Data Key Stego Object Original Cover Secret Data Communications Channel

7. Basic Types of steganography Substitutional Steganography Elements of the redundant covering medium are substituted by the elements of the stego medium. Selecting Steganography Elements of the covering medium are selected to carry the hidden information. The relevant information is hidden in a narrow- band region of a wide band noise. Constructional Steganography The Stego message is made similar to the structure of the covering medium. Steganograph y 7

8. Techniques of steganography Altering LSB (most commonly used) Masking Filtering Transformations Steganograph y 8

9. Altering LSB Uses LSB of each pixel in the image Neccessary to use a lossless compression format A 24 bit color image, 3 bits (one each from RGB) available for each pixel So, a 800 × 600 pixel image supports 180.000 bytes of secret data Steganograph y 9

10. Altering LSB For example, (00100111 11101001 11001000) (00100111 11001000 11101001) (11001000 00100111 11101001) When the character A (10000001), is inserted, the following grid results: (00100111 11101000 11001000) (00100110 11001000 11101000) (11001000 00100111 11101001) Steganograph y 10

11. Masking and Filtering Use luminence part of image Suitable for compression Robust and efficient Steganograph y 11 Transformations Direct Cosine Transform is applied to 8x8 blocks Complex to create and decode

12. Feasibility and Constraints Visual percievable differences Amount of data that can be hidden Vulnerabilty Steganograph y 12

13. Visual percievable differences Type of cover image e.g. grids Size of hidden data Type of hidden data and the bits it is dedicated Steganograph y 13 Cover Image Hidden Image ( Originals ) Cover Image Hidden Image (7 bits)(1 bit) Cover Image Hidden Image(4 bits) (1 bit)(7 bits) 5 % text 20 % text

14. Amount of Hidden Data Depends on number of bits being distorted in the spatial domain Tradeoff between space available and visual difference Proportional to the enclosed spaces availaible Steganograph y 14 Default1 Bit2 Bits3 Bits4 Bits5 Bits6 Bits7 Bits8 Bits

15. LSB hiding in 24 bit bmp picture Sufficient space available for most purposes Steganograph y 15 After stegno ( contains 4862 hidden letters)Original Containing hidden information Bitmap308 614 bytes JPG21 795 bytes21 952 bytes

16. Applications Security implementations Digital Watermarking Storing content metadata Steganograph y 16

17. Security implementations Better than cryptography as it doesn’t attract any suspicion Posting secret communications on the Web to avoid transmission Hiding data on the network in case of a breach Steganograph y 17

18. Digital Watermarking Copyright protection Link to owner’s webite to buy product Broadcast monitoring Source tracking Covert communication Steganograph y 18

19. Storing content metadata Data can be stored as XML, Exif, XMP, PLUS etc Used to store date photo taken, location, camera info, exposure Keywords help in searching for images Geotagging allows better sorting Steganograph y 19

20. Threatening Implementations Covert and subversive operations Terrorism Weapons and narcotics traffickers Money laundering Insider stock trading People who want to circumvent encryption export rules. Steganograph y 20

21. Tools Steganos S-Tools (GIF, JPEG) StegHide (WAV, BMP) Invisible Secrets (JPEG) JPHide Camouflage Hiderman Many others… Steganograph y 21

22. References http://www.computerworld.com/s/article/71726/Stegan ography_Hidden_Data Paper on Information hiding by Soldatov Nikolay Paper on Steganography, Steganalysis, & Cryptanalysis by Michael T. Raggo, CISSP, Principal Security Consultant, VeriSign Case Study: An Implementation of a Secure Steganographic System by Xuan-Hien Dang and Krishna C. S. Kota http://www.sans.org/reading_room/whitepapers/covert /detailed-steganographic-techniques-open-systems- environment_677 Steganograph y 22