STEGANOGRAPHY: Information Hiding

1. STEGANOGRAPHY: Information Hiding SOUNDARARAJAN EZEKIEL Department of Computer Science Indiana University of Pennsylvania Indiana, PA 15705

2. WELCOME AND THANKS • I welcome Every One • I would like to Thank • Dean • Chair • Dr. Micco • Colleagues • Students

3. Why do I want to talk about Steganography • Information Security undergone two major changes Network Security Computer Security Distributed system– use of network— Communication facilities– carrying Data between – Measure needed to protect data Protect data Olden days– filing cabinet With a combination locks for storing sensitive document Modern days:- With introduction of the computer – protecting files is important Example:- virus, Source Normal Destination interruption interception modification fabrication

4. Why do I want to talk about Steg ? • Digital Information revolution changed our lives– generated new challenges and opportunities. • Software, digital camera, MP3 player, PDA (personal digital assistant) have attracted consumers worldwide– create, manipulate, and enjoy multimedia data • Internet and wireless network—deliver and exchange information • Security and fair use of data are important yet challenging topics

5. Why do I want to talk about Steg ? • Solutions to these problems help us to understand the fast moving technology • I am going to talk about the issues regarding multimedia information hiding and its applications in multimedia security and communications • Different names:- • Steganography • Data hiding • Information hiding • Digital watermarking

6. What is the difference between Steganography and Cryptography Art of hiding information in ways that prevent the detection of hidden message Existence is not know Science of writing in secret code It encodes a message so it cannot be understood

7. Cryptography • Cipher- Cryptosystem– Encrypt • Map S------- T • Plain text –--- Cipher text • K– enciphering key • Decipher/decrypt—decoding----inverse • Deciphering key k’ • k=k’ or k’ is computable from k– symmetric, single key, secret key • K!=k’ or k’ is very hard to derive from k then k’= asymmetric, two key, public key • Type of operation– keys– plain text processing • Cryptography– study of concealing information, using mathematical transformation– cryptographer • Cryptanalysis– revealing information hidden by cryptography using analytical or mathematical analysis • Intelligence– spying the system, stealing decryption, brining cryptographer, injecting him with truth serum, pointing light/gun in his face, bashing him over the head with bricks, other tactics • Example : Encrypt.exe

8. An Illustration of a bucket array 0 1 2 3 4 5 6 7 8 The bucket for item 6 with Key=6

9. Arbitrary Objects Hash code -3 -2 -1 0 1 2 3 Compression map 0 1 2 3 …. N-1 The two parts of a hash functions: a hash code and a compression map

10. TITLE Encryption Program INCLUDE Irvine32.inc KEY = 239 BUFMAX = 128 .data sPrompt BYTE "Enter the plain text: ",0 sEncrypt BYTE "Cipher text: ",0 sDecrypt BYTE "Decrypted: ",0 buffer BYTE BUFMAX dup(0) bufSize DWORD ? .code main PROC call InputTheString call TranslateBuffer mov edx,OFFSET sEncrypt call DisplayMessage call TranslateBuffer mov edx,OFFSET sDecrypt call DisplayMessage exit main ENDP • mov bufSize,eax • call Crlf • popad • ret • InputTheString ENDP • DisplayMessage PROC • pushad • call WriteString • mov edx,offset buffer • call WriteString • call Crlf • call Crlf • popad • ret • DisplayMessage ENDP • TranslateBuffer PROC • pushad • mov ecx,bufSize mov esi,0 • L1:xor buffer[esi],KEY • inc esi • loop L1 • popad • ret • TranslateBuffer ENDP • END main InputTheString PROC pushad mov edx,offset sPrompt call WriteString mov ecx,BUFMAX mov edx,offset buffer call ReadString

11. Steganography-- History • Greek origin -- meaning “ covered writing” • History goes back to BC 400 • Herodotus ( c486-425 B.C.) tells around 400BC how Histiaeus shaved the head of his most trusted slave and tattooed it with a message which disappeared after the hair had re-grown– purpose was to instigate a revolt against the Persians • Message written on table– waxed, painted • Notes carried by pigeons • Invisible ink– milk or urine – use heat to see • Small holes above or below letters– see with light • 1860’s– images are used to hide information • During WWI– Father is dead– modified as Father deceased--- Reply telegram went – Is Father dead or deceased?

12. Fishing freshwater bends and saltwater coasts rewards anyone feeling stressed. Resourceful anglers usually find masterful leapers fun and admit swordfish rank overwhelming anyday. • Send Lawyers, Guns, and Money • Apparently neutral's protest is thoroughly discounted and ignored. Isman hard hit. Blockade issue affects pretext for embargo on by-products, ejecting suets and vegetable oils.  • Pershing sails from NY June 1 • We explore new steganographic and cryptographic algorithms and techniques throughout the word to produce wide variety and security in the electronic web called the Internet. • We explore new steganographic and cryptographic algorithms and techniques throughout the word to produce wide variety and security in the electronic web called the Internet. • EXPLORE THE WORLD WIDE WEB

13. Steganography– Methods-- Category Data Hiding Techniques • Embedded data is called Watermark(s) Perceptual Sources Non Perceptual sources Audio, Images, Video, 3-D Graphics Lossy Compression Text Executable codes Lossless Processing

14. Application Domain Ownership Protection: Ownership is embedded in the media Authentication or Tempering Detection:- Set of secondary data embedded to determine the host media is tampered or not---Blind detection Fingerprinting or Labeling Used to trace the originator or recipients of a particular copy of multimedia copy Copy Control or Access Control Copy control access control policy– DVD copy control or SMDI activities Annotations:- Convey any message– no robustness

15. Steganography of today’s talk Stegokey Password • The steganography of today’s talk is about digital images ( video, audio) as mediums Stego-Meida Cover Media ( Carrier) S S Steganography Application Message to Hide Carrier with the Hidden message Cover medium+ embedded message+stegokey== stego-medium

16. Embedding Function Extracting Function Cover image Stego 101011101011 101100100100 100011010111 101011101011 101100100100 100011010111 101011101011 101100100100 100011010111 101011101011 101100100100 100011010111 Extracted Message Message to embedded

17. Lets Talk about Image X0(100,100)= ( 237, 211,214)—RGB =( 11101101, 11010011, 11010110) Color– V I B G Y O R 380 NM -- 780 NM FREQUENCEY – 370-750 trillion HZ Speed= 300,000 km/sec Wavelength= speed/ freq Binary Image– two color Gray Image– Color Image Pixel– Pixel Element X(100,100)=219 11011011

18. Steganography Methods • Lets us discuss few methods and its advantage and disadvantage • 1. Least Significant Method • Idea:- Hide the hidden message in LSB of the pixels • Example:- • Advantage:- quick and easy– works well in gray image • Disadvantage:- insert in 8 bit– changes color– noticeable change– vulnerable to image processing– cropping and compression

19. Redundant method • Store more than one time--- withstand cropping • Spread Spectrum • Store the hidden message everywhere • STEGANALYSIS • Detection Distortion Analyst manipulate the stego-media To render the embedded information Useless or remove it altogether Analyst observe various Various relationship between Cover, message, stego-media Steganography tool Seeing the Unseen

20. DCT - Discrete Cosine Transformation 219 215 214 216 218 218 217 216 219 216 216 216 215 215 215 215 217 217 218 216 212 212 213 215 215 215 215 215 211 212 214 216 217 216 214 216 215 215 217 218 216 216 215 214 215 215 215 216 215 214 210 210 211 215 215 216 218 215 211 211 213 214 216 216 • Encode • Take image • Divide into 8x8 blocks • Apply 2-D DCT--- DCT coefficients • Apply threshold value • Store the hidden message in that place • Take inverse– store as image • Decode • Start with modified image • Apply DCT • Find coefficient less than T • Extract bits • Combine bits and make message 1720 1.524 7.683 1.234 1.625 0.9234 -0.07047 -1.055 5.667 3.475 -4.181 -1.524 1.152 1.637 1.016 0.3802 0.3711 -1.442 1.067 5.944 0.3943 -0.4591 0.1313 0.7812 3.888 -3.356 -1.97 3.265 0.5632 -0.939 -0.2434 0.2354 1.625 -2.279 0.4735 1.392 1.375 0.6552 -1.143 0.03459 -4.049 -1.223 0.5466 -0.5425 -1.013 -0.2651 0.5696 -0.9296 1.876 1.924 -1.369 -1.132 -0.02802 -0.4646 0.1831 0.9729 0.8995 -0.7233 0.667 0.436 0.1325 -0.03665 -0.3141 -0.4749

21. Wavelets Transformation Wavelets are basis function in continuous time. a basis is a set of linearly independent functions that can be used to produce all admissible functions f(t) The special feature of wavelet basis is that all functions are constructed from a single mother wavelet w(t). This wavelet is is a small wave ( a pulse). Normally it starts at time t=0 and end at time t=N Shifted k time = Compressed = Combine both we have Haar Wavelet :- 1909 Haar, 1984– theory, 88– daubechies 89- Mallat 2-d, mra, -- 92- bi-orthogonal Haar=

22. Carrier Stego image Wavelet Transformation Thresholding Compression Messageto be Hidden Error Image Inverse Transformation Extract the Hidden Message

23. Discussion • Noise – we are running into a problem • RMS( Root Mean Square Error) • PSNR( Peak-Signal-to-Noise- Ratio) 5- 42, 10-37, 20-34, ….. 60- 29 • Future Work:- Explore hiding information in detail coefficients • Combine:- Cryptography with Steganography • Check for Robustness--- ( Attacks– Processing, modifying….)