Technical Aspects of Digital Rights Management Emilija Arsenova MI, RWTH-Aachen

Digital Intellectual Property Digital media properties Digital content (audio, video, graphics, images) can be easily copied, transmitted and distributed Exact copies of the original data Problem for content owners/providers?

Digital Rights Management I System for protecting the copyrights of data circulated via the Internet or other digital media by enabling secure distribution and/or disabling illegal distribution of the data http://lib.colostate.edu/lingo/d.html

What Does DRM Really Mean? You can play your new audio CD on your stereo system, but when you insert it into the CD drive on your Macintosh computer, the CD doesn't work. Worse still, the machine crashes and refuses to reboot. The disc remains stuck in the drive until you force the tray open by inserting a paper clip. You buy an e-book and discover you can read it on-screen but can't print a chapter, even though the book is by Dickens and entered the public domain more than a century ago. http://www.pcmag.com/article2

Digital Rights Management II DRM = digital restriction management ?

Digital Rights Management III DRM - commonly advertised as the technology that can restore the value of content ‘DRM is a system of IT components and services, corresponding law, policies and business models which strive to distribute and control IP and its rights’ (www.eu.int )

DRM Focus "DRMs' primary role is not about keeping copyrighted content off P2P networks. DRMs support an orderly market for facilitating efficient economic transactions between content producers and content consumers." Dan Glickman, Motion Picture Association of America, to BBC NEWS

DRM Architecture http://www.dlib.org/dlib/june01/iannella/06iannella.html

DRM Goals Protection of digital content Secure distribution Content authenticity Transaction non-repudiation (digital signature) Market participant identification (digital certificates)

DRM Techniques Encryption Public / private keys Digital certificates Watermarking Access control Secure communications protocols Fingerprinting Rights specification language Trust infrastructure Hashing

Security goals http://www.inf.tu-dresden.de/~hf2/

Protection of digital content Encryption scramble data to make it unreadable to everyone except the recipient Decryption recovering the original bits

Encrypting the file – is it enough? Managing the decryption key: creating it transferring it to the customer enforcing any time limitations changing user rights preventing theft or transfer of the key

Watermarking Steganography (covered writing) Digital Watermarking

Why Use Watermarking? Ease of replication Ease of transmission and multiple use Exact copies of digital data Permanently mark the data

Watermark Applications Proof of ownership Prove ownership in a court of law Broadcast monitoring Keep track of when and where a clip is played Owner identification Transactional watermarks (Fingerprinting) Identifying the source of an illegal copy www.digimarc.com

Watermark Applications Copy Control Prevention of illegal copying Classification/Filtering Classification of content Authentication www.digimarc.com

Types of watermarks Visible, invisible Fragile, robust Blind, semi-blind, non-blind

Visibly watermarked ‘Lena’ Original picture Watermark images Smaller watermark Bigger watermark M. Kankanahalli, et. al., ”Adaptive Visible Watermarking of Images”

Embedding and detecting systems P P Chun-Shien Lu, Multimedia security: Steganography and digital watermarking techniques for protection of intellectual property

Ideal watermarking system perceptibility robust image compression protection of malicious attacks capacity speed

Digital Watermarking Techniques choice of watermark object spatial domain transform domain fractal domain

Choice of watermark object what form should the embedded message take?

Spatial Domain Techniques Addition of pseudo-random noise LSB modification Replace the LSB of each pixel with the secret message Pixels may be chosen randomly according to a key Drawbacks highly sensitive to signal processing operations easily corrupted

Example:LSB Encoding (R,G,B) = (00000000, 11111111, 00000000)

Transform Domain Techniques Wavelet based watermarking Most efficient domain for watermark embedding HVS DCT-based watermarking Fractal domain watermarking Computational expense Not suitable for general use

Robustness How robust are watermarking algorithms?

Testing watermarking algorithms Image watermarking algorithms must survive robustness attacks Geometric distortions Combinations of geometric distortions

Example – StirMark Tool Applies: Large set of different geometric distortions The image is slightly stretched, shifted, bent and rotated by an unnoticeable random amount Frequency displacement and deviation Embeds a small error in each sample value

Applying StirMark to images I Before StirMark After StirMark Copyright image courtesy of Kevin Odhner (jko@home.com)

Applying StirMark to images II Underlying grid Grid after StirMark Fabien A. P. Petitcolas and Ross J. Anderson, Evaluation of copyright marking systems

Questions?

THANK YOU!