Technical Aspects of Digital Rights Management

Emilija ArsenovaMI, 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

RIGHTS

USERS CONTENT

OVEROWN

CREATE/USE

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

INTEGRITY PROTECTION

SECURITY GOAL

CONDITIONAL ACCESS COPY

PREVENTION

DETECTION

PROTECTION OFOWNERSHIP

ENCRYPTION

TAMPERRESISTANT

HW DEVICES

FINGERPRINTING

WATERMARKING

TECHNIQUES

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’

Smaller

watermark

Watermark

images

Original

picture

Bigger

watermark

M. Kankanahalli, et. al., ”Adaptive Visible Watermarking of Images”

Embedding and detecting systems

P

P

ORIGINALMEDIASIGNAL

WATERMARKEDMEDIA SIGNAL

ENCODER

KEY

WATERMARK

PIRATEPRODUCT

ATTACKEDCONTENT

DECODER

KEY

DECODERRESPONSE

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) (R,G,B) = (00000001, 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?

W

LOSSYCOMPRESSION

GEOMETRICDISTORTIONS

SIGNALPROCESSINGOPERATIONS

WATERMARKEDIMAGE OR SOUND

W

CORRUPTEDWATERMARKED

IMAGE OR SOUND

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 StirMarkCopyright image courtesy of Kevin Odhner (jko@home.com)

Applying StirMark to images II

Underlying grid Grid after StirMarkFabien A. P. Petitcolas and Ross J. Anderson, Evaluation of copyright marking systems

Questions?

THANK YOU!