Multimedia Security Part I: Digital Watermarking Subrata Acharya CS 2310, Spring 2007

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

How It Works

Data Hiding

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

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. 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. Overlay the watermark in a way which makes it difficult to remove, if the goal of indicating property rights is to be achieved.

Visible Watermark

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

Invisible Watermark

Embedding Techniques Spatial domain Spatial domain Original needed Original needed Original not needed Original not needed Frequency domain Frequency domain Original needed Original needed Original not needed Original not needed Spread domain Spread domain

Spatial Domain

Frequency Domain Watermarking signal to embed Watermarking signal to embed Host signal Host signal Frequency components Frequency components Embedding Embedding Extraction Extraction

Frequency Domain

Spread Spectrum

Applications of Watermarking Rights management Rights management Contents management Contents management Access/copy control Access/copy control Authentication Authentication

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

Technical Requirements for Watermarking Invisibility CapacityRobustness

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

Digital Watermarking Alliance Members

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

Potential Usage Models and Benefits User Software Usage Models Detect Copyright DWM Detect Content ID Copyright Communication P2P systems only distribute non-copyright content Licensed Content P2P systems can resell copyrighted content with license agreements with content owners Enhanced Content P2P systems provide or sell media content information and related items

Copyright Digital Watermark Architecture Audio/Video Master Embed Copyright and Content ID DWM Content Owner Provider Index Database Location (Centralized or Distributed) User’s PC Rip Software Compressed Audio/Video File (e.g. MP3 file) User Software Detect Copyright and Content ID DWM for Secure and Enhanced content Rights & Info Database Content ID linked to rights, information and related content 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

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. 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 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 May be key element of identifying copyrighted content to support legitimate P2P distribution  Copyrighted Non-Copyrighted Content Filter Access Legitimate Copy or License

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

Digital Media Serialization & Tracking Protected for privacy Identifies content owners and rights while communicating copyright information Identifies content owners and rights while communicating copyright information Awareness of watermarked content by consumer creates deterrent against unauthorized copying and distribution 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 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 Recordable Media Embed Serial # (2) Embed Serial # (1) Content ID Retail Content Content Provider Track and take proper action Detect Serial Number

Multimedia Security Part II: Encryption Subrata Acharya CS 2310, Spring 2007

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

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

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

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

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

Randomized Huffman Table Encryption A 0 1 B C D E F G A 0 1 B C D E F G 0 0 BADCAEFG Huffman code #0 Huffman code # isomorphic tree!

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

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

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

Thank you !!!