Overview of DVD Copy Protection Methods, With Emphasis on Digital Watermarking James Painter EGR 230

Movie Piracy About $3 billion lost annually Difficult in days of VHS Relatively easy now, since DVD encryption has been cracked (1999)

Series of decryption keys Relatively simple 40-bit encryption compared to todays standard 128-bit Short lived, but lessons learned Method 1: Content Scrambling System

Method 1: CSS

Method 2: Copy Generation Management System Two bits embedded in DVD video indicating one of four copy states DVD recorder reads copy state, terminates burn if necessary

Method 2: CGMS Two bits = 2 2 = 4 possible copy states: CGMS BitsMeaning 0, 0Copying is permitted without restriction 0, 1 Condition not to be used (No more copies in EIA-805) 1, 0One generation of copies may be made 1, 1No copying is permitted

Method 2: CGMS CGMS bits transmitted through television broadcasts –PVR, DVD recorder Problems –Non-compliance leads to CGMS bit deletion –Loose regulation

Information (literally text) embedded in every video frame –Owner identification –License information –Misc. video details –Indicators of previous copy attempts –CGMS copy states Method 3: Digital Watermarking

Method 3: Watermarking DVD recorder searches for watermarks, blocks burn if copyrighted material Also used for tracking ripped DVDs –Search engines

Method 3: Watermarking Implementation in camcorders prevent piracy within the theater Digital watermarks can be embedded in television broadcast signals (similar to station logos)

Method 3: Watermarking Watermarks of varying focus levels Flat mask vs. Gradual mask Allows brightness increases of up to 16% while preserving invisibility

Method 3: Watermarking Original image with no watermark (left), watermarked image (center), difference between the original and watermarked images (right)

Method 3: Watermarking Images without watermark (top), images with watermark (bottom)

Method 3: Watermarking Effects of false positives False positive probability minimized to less 4.7x10 -23

Method 3: Watermarking Attempts to remove watermarks will cause severely garbled pictures Possible future implementation in other consumer electronics

Though CGMS (Method 1) is ineffective by itself, copy states embedded within a watermark can accomplish CGMSs goal –Difficulty of removal –Survives digital-to-analog conversion Combination of Methods

Concluding Remarks Cooperation among industries with differing interests Nothing will stop the determined hacker Keeping honest people honest

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