Multimedia Security Part I: Digital Watermarking

1. Multimedia SecurityPart I: Digital Watermarking Subrata Acharya CS 2310, Spring 2007

2. Digital Watermarking? • Allows users to embed some data into digital contents • When data is embedded, it is not written at header part but embedded directly into digital media itself by changing media contents data

3. How It Works

4. Data Hiding

5. Types of Watermark • Visible • A visible translucent image which is overlaid on the primary image • Invisible • An overlaid image which cannot be seen, but which can be detected algorithmically

6. Visible Watermark • Logo or seal of the organization which holds the rights to the primary image, it allows the primary image to be viewed, but still marks it clearly as the property of the owning organization. • Overlay the watermark in a way which makes it difficult to remove, if the goal of indicating property rights is to be achieved.

7. Visible Watermark

8. Invisible Watermark • Embedding level is too small to notice • Can be retrieved by extraction software • Applications: • Authentication • Copyrighting • Etc…

9. Invisible Watermark

10. Embedding Techniques • Spatial domain • Original needed • Original not needed • Frequency domain • Original needed • Original not needed • Spread domain

11. Spatial Domain

12. Frequency Domain • Watermarking signal to embed • Host signal • Frequency components • Embedding • Extraction

13. Frequency Domain

14. Spread Spectrum

15. Spread Spectrum

16. Applications of Watermarking • Rights management • Contents management • Access/copy control • Authentication

17. Features of Watermarking • Invisible/Inaudible • Information is embedded without digital content degradation, because of the level of embedding operation is too small for human to notice the change. • Inseparable • The embedded information can survive after some processing, compression and format transformation. • Unchanging data file size • Data size of the media is not changed before and after embedding operation because information is embedded directly into the media.

18. Technical Requirements for Watermarking Invisibility Robustness Capacity

19. Digital Watermarking Alliance Represents applications and solutions for: • Audio and Music Content • Video, Movies and TV Content • Digital Imagery • Identity Documents • Value Documents

20. Digital Watermarking Alliance Members

21. Digital Watermarking Examples • Copyright Communication • Copy Protection • Monitoring • Filtering/Classification • Authentication/Integrity • Product Serialization & Tracking • Asset/Content Management • Rights Management • Remote Triggering • Linking/E-Commerce

22. Potential Usage Models and Benefits User Software Usage Models Copyright CommunicationP2P systems only distribute non-copyright content Detect Copyright DWM Licensed ContentP2P systems can resell copyrighted content with license agreements with content owners Detect Content ID Enhanced ContentP2P systems provide or sell media content information and related items

23. Content Owner User’s PC Audio/Video MasterEmbed Copyrightand Content ID DWM Rip SoftwareCompressed Audio/VideoFile (e.g. MP3 file) User SoftwareDetect Copyright and Content ID DWM for Secure and Enhanced content Rights & Info DatabaseContent ID linked to rights, information and related content Provider Index Database Location(Centralized or Distributed) Copyright Digital Watermark Architecture Can be used to address P2P and social network content Identification needs as well as providing identification of orphan works and access to metadata/networked information

24. Filtering & Classification • Can support existing, established and/or new Classification Systems or content identifiers such as MPAA film ratings, ISAN or ad identification codes, etc. • Filtering can occur at the whole content level and/or at a more granular level identifying copyrighted, sensitive and/or questionable material for the given audience • May be key element of identifying copyrighted content to support legitimate P2P distribution Access Legitimate Copy or License Copyrighted  Non-Copyrighted Content Filter

25. Captured CD e-logo links to web and music downloads DOWNLOAD • Ring tones • Buy tickets • Reviews • Tour dates • Samples • Band info Connected Content/Linking • Promoting & Facilitating M-Commerce • Location based services • Multimedia access • Streaming audio • Music • Multimedia • Bookmarking

26. Retail Content Recordable Media EmbedSerial # (2) EmbedSerial # (1) Content ID Content Provider Track and take proper action DetectSerial Number Digital Media Serialization & Tracking • Identifies content owners and rights while communicating copyright information • Awareness of watermarked content by consumer creates deterrent against unauthorized copying and distribution • Provides accurate identification of source of unauthorized content discovered on the Internet and/or physical media (1) At Point of Distribution (2) At point of copying/re-distribution Protected for privacy

27. Multimedia SecurityPart II: Encryption Subrata Acharya CS 2310, Spring 2007

28. Goals • Person authentication • Assurance that the communicating entity is the one claimed • Access control • Prevention of unauthorized use of a resource • Data confidentiality • Protection of data from unauthorized disclosure • Data integrity • Assurance that data received is as sent • Non-repudiation • Protection against denial by the parties in a communication

29. Multimedia Data What separates multimedia data from traditional alpha numeric data? • Large in file size • May require real-time processing (especially for continuous media) • Portable and mobile applications

30. Multimedia Encryption Approach • Signal scrambling • Historical approach • Not compatible with modern multimedia compression • Fast speed but low security • Total encryption with cryptographic ciphers • Trivial solution • High security but slow speed • Selective encryption • Most popular approach today • Limited in its range of application • Integrating encryption into entropy coding • Complementary to selective encryption • Very fast computation speed

31. Selective Encryption • Select the most important coefficients and then encrypt them with traditional ciphers such as DES • Advantages • Lower complexity • High security level provided by traditional cryptology • Less error correction coding redundancy • Compatible with existing software and hardware modules Media Compression System Coefficient Selection Cryptographic Cipher Coefficients Digitized Audiovisual data Selected Coefficients Error Correction Coding Non-selected Coefficients Transmission channel or storage media

32. + Example: Selective Encryption for G.723.1 Speech Coder • ITU-T Recommendation G.723.1 • A popular low bit rate speech codec • Based on the human voice generation model • Vocoder • Decoder synthesizes speech using the model LSP codebook indices LSP Decoder LSP Interpolator Vocal Tract Linear filter Lag of pitchpredictors Gain vectors Pitch Decoder Pitch Postfilter Synthesis Filter Formant Postfilter Excitation Decoder Fixed codebook gains and others Gain Scaling Unit Vocal Cord Excitation signal generation

33. 00000000 10011010 Randomized Huffman Table Encryption 1 1 0 0 1 0 0 1 A A 1 1 0 0 0 1 0 1 0 1 1 0 0 1 0 1 C B C B G E D F G E D F isomorphic tree! Huffman code #0 Huffman code #1 100011001010110111101111 BADCAEFG 110011001110110110111111

34. 1110 KHS = 011000110 … s PRBG Multimedia Encryption with Randomized Entropy Coder • Select a good PRBG • Select an r-bit random seed s (encryption key) • Pseudo-random sequence output from PRBG(s) becomes the key hoping sequence (KHS) Entropy Coder Input symbol 1110 101 110001…

35. Challenges • Real time constraint • Potential cost constraint • Potential bit rate increase • Rate variation challenge • Dynamic network conditions • Transcoding challenge

36. Conclusion • Multimedia security relevance • Tradeoff approach based on application • Goal is the design of an • efficient, • secure and • cost effective technique for multimedia security using digital watermarking and encryption

37. Thank you !!!