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Digital Rights Management for Visual Content in Mobile Applications

Trimeche, M.; Chebil, F.;Nokia Research Center

Control, Communications and Signal Processing, 2004. First International

Symposium on, 2004. Pages:95 - 98

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Outline

Introduction DRM in OMA DRM for Mobile Visual Content

Encryption Watermarking Watermarking of images and video

Conclusion

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Introduction Secure distribution, storage,

exchange and management of copyright-protected contents Audio Video Game,…

A balance between content owner and consumer’s rights

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Conflicts of Rights

Content Owners I create the content Revenue flow for every single copy

sold No resale of content No copying of content Content used only by original buyer Limited use of content

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Conflicts of Rights(Cont.)

Consumers I paid for the content Fair use right to copy the content Resale the content in a different form Share contents with others Unlimited use of contents Why pay for something if I can get it

free

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DRM System End-to-end security

Every link in the delivery chain has to be secured 2 major content distribution channels

Distribution of electronic files via the Internet or digital bus interface

Distribution via pre-recorded or recordable physical media

Only accessible to authorized/authenticated person or compliance devices Rights are correctly executed and enforced

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DRM Formula DRM = Contents + Rights + Enforcement Contents

Audio track, VCD, DVD, … Rights

Copy once, copy never, unlimited listening, 10 downloads per day, …

Enforcement Rights executed as specified with technology

and legal support

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DRM in OMA OMA (Open Mobile Alliance)

Formed in June 2002 By “Open Mobile Architecture

Initiative” and “WAP Forum” Introduce/Promote open standards

and specifications for mobile industry OMA DRM V2.0 3GPP move the MDRM(Mobile DRM)

standardization to OMA

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DRM in OMA(Cont1.) Right expression

4 key components Principal (user, compliance devices) Rights (copy, play, download, view, print,…) Resource (the digital content) Condition (when, how, how much times,…)

Example Registered user 8043 can have 10 downloads

from compliance device 132 starting from time xxx to time yyy

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DRM in OMA(Cont2.) DRM package includes

Rights Define how the device is allowed to render

the content Copy, play, download…

The usage right REL(Right Expression Language)

A language to specify rights and their condition ODRL (Open Digital Right Language) Support an extensible language and data

dictionary

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DRM in OMA(Cont3.) Based on public key cryptography to

enhance security support 3 download modes

Forward Lock Allows single purchase and single delivery Content cannot forwarded to other devices Clear content WAP download

Combined Delivery Clear content + rights WAP download Device conforms to rights Enable usage rules to be sent for the media object Add a RO(Right Object) to the DRM message

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DRM in OMA(Cont4.) Separate Delivery

Protect higher-value media and enable right refreshment

encrypted content WAP download Rights + key separately delivered

Super distribution and separate channel Media is encrypted into DCF(DRM Content

Format) Use symmetric encryption

The rights hold the CEK(Content Encryption Key)

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DRM in MPEG MPEG-4 IPMP

Separate content stream (IPMP-ES) and associated rights (IPMP-Ds)

Provides an interface between DRM-specific content and MPEG-4 terminal

MPEG-21 IPMP An open interoperable framework for multimedia

delivery and exchange Content encapsulation in Digital Item (regardless of

format) REL standardized a way to associate rights with

content The MPEG-21 REL is an XML-based language

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DRM for Mobile Visual Content

Multimedia portable device Small display size (screen) Power management Processor utilization

Lower computational and memory capability Security issue Fulfill strict quality and bit rate

requirement in real-time streaming application

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Encryption

Content encryption Block cipher technology

DES (Data Encryption Standard)

Selective encryption Only encrypt the compressed code

stream header Only Intra frames could be encrypted

in video

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Watermarking

Embedded information into digital content irremovably and invisibly

Technology has its limitation Keep watermarking casting secret False alarm is more severe than

missing Can still be a valuable component in a

DRM system

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Watermarking(Cont.)

Fig. 2 shows that the use of watermarking to enhance DRM security MMS (Multimedia Message Service)

content Stamp watermarks into the media

object It’s only a stand-alone solution, not

part of any OMA Spec.

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Watermarking of images and video Capacity

Low-resolution image The carrier signal has lowered bandwidth A smaller capability for data hiding

Content adaptation Watermark has to resist content

adaptation It can consist of spatial subsampling of

images/video to fit display size, color space reductions, or format conversion, …

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Watermarking of images and video(Cont.)

Computational complexity Watermark has to be simple to

extract Security issue

Further study of preventing abuse and security leakage strategy have to be carried out in open mobile platform

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Conclusion

Propose a system that integrate watermarking technology to stamp media content in MMS

The limitations and requirements of the mobile visual content should be taken into consideration in mobile application