Digital Rights Management – the other way around

Transcription

Digital Rights Management –
the other way around
Virtual Goods 2003
Prof. Dr.-Ing. Karlheinz Brandenburg
TU Ilmenau, Institut für Medientechnik
Fraunhofer IIS,
Arbeitsgruppe Elektronische Medientechnologie
Ilmenau
[email protected]
Prof. Dr. Karlheinz Brandenburg, [email protected]
Page 1
Fraunhofer
Institut
Integrierte Schaltungen
Overview
•
mp3 and the music industry: early experiences
•
Early DRM systems
•
Parts of the technology puzzle
•
What does not work ?
•
“the other way around”:
•
Conclusions
Page 2
Fraunhofer
Institut
LWDRM
MP3 and the Digital Distribution of Music
MP3 and the music industry
Early DRM systems
SDMI
Page 3
Fraunhofer
Institut
MP3: What it did to music on computers
•
With the arrival of MP3 encoding/decoding
– 12 times more storage of music on computers
– 12 times more music on a CD-ROM
– cut download time of music by 12
•
1996/1997: students discover MP3
– several decoders are written
– Web servers with pirated content pop up
– June 97: The RIAA closes down three web sites and
gets nation wide press coverage:
– more pirated material, more usage of MP3
Page 4
Fraunhofer
Institut
MP3 proliferation: A little bit of history
•
1998:
– The first flash memory based mp3 player shows up:
The Saehan mpman
– Diamond buys a company with rights to the design
(the original developers of the mpman)
– RIAA gives nation wide advertisement for the
Diamond Rio by unsuccesfully trying to stop the sale
via court orders
•
1999:
– Thomson licensing moves to San Diego
– RealNetworks, Apple etc. license mp3
– Jukebox applications attract millions of users
– 96 kbit/s free distribution is added as a business
model
– The RIAA announces the SDMI
•
2002:
– Music industry announces big drop in turnover
Page 5
Fraunhofer
Institut
Early DRM systems
Did anybody ever think of “secure mp3” ?
•
1995:
MODE-consortium
•
Ricky Adar: “destroy the music industry” ?
•
mmp and other early systems
– Secure envelope technology
– Simple cryptografic methods
– Low complexity
– Simple key management
•
•
Liquid Audio
Intertrust
Page 6
Fraunhofer
Institut
SDMI (Secure Digital Music Intitiative)
•
Set up by RIAA, IFPI, RIAJ to establish a legal alternative
to MP3 with no protection
•
100s of companies from
– music industry (record labels)
– IT industry
– CE industry
– research labs
•
Short track
– PDWG, looking for portable devices spec until June
30th., 1999: not enough interoperability
•
Work since July, 1999
– Screening (for keeping illegal files out)
– Decision against interoperability (!!
•
Summer of 2001: SDMI goes dormant
Page 7
Fraunhofer
Institut
The Technology Puzzle
Authentication
Secure Envelope Technologies
Watermarking
Page 8
Fraunhofer
Institut
Overview of Current Technologies
•
Authentication
– Maintain the integrity of data by calculating hash
sums etc.
– Proof of identity via public key kryptography
•
Scrambling / Encryption
– Modify the content to enable replay only if the
correct decoding key is applied
•
Watermarking
– Hide data in the audio signal itself
– Can survive manipulation of the audio signal
•
Identification
– Recognize music tracks even if modified/edited
Page 9
Fraunhofer
Institut
Protection by Authentication
•
Secure hash sums (e.g. MD5) are already in widespread
use
•
Hash sums can be used to
– show the integrity of a file
– secure header information from tampering
– find hints that unauthorized compression /
decompression has happened
•
Copyright protection by authenticated header
(for example Liquid Audio Genuine Music Mark)
– Maintain compatibility with equipment playing
unprotected content (e.g. .mp3)
– User friendly, but not secure
Page 10
Fraunhofer
Institut
Secure Envelope Technologies
•
Modify the music in a way that only users with the right
key have an undisturbed listening experience
•
Normal method:
– scramble the compressed bit stream
– only the right key gives the right descrambling
•
Fraunhofer Audio Scrambling:
– scramble the signal but maintain decodability
– gives a degrades preview if not descrambled
•
A number of secure envelope systems have been
developed by:
– Cerberus, A2B (AT&T), Liquid Audio, Fraunhofer,
Intertrust, IBM, Sony, Microsoft etc.
Page 11
Fraunhofer
Institut
Security issues for scrambling technologies
•
•
•
•
•
•
The presence of a master key would be a single point of
failure
Encryption technology may be needed:
Export / usage restrictions may apply
Simple encryption might be broken easily on tommorows
computers
Advanced encryption may add too much complexity to a
system
Moving music to a different system can imply decryption
/ encryption, putting the full technology on the users
premises
None of the systems described above has been broken
yet
Page 12
Fraunhofer
Institut
Watermarking
•
Embed a (hopefully) inaudible / invisible signal into the
audio
•
Perceptual encoding tries to transmit only the audible
parts of a signal:
– Watermarking lives only in the space left by less
than ideal perceptual encoding
•
Spread spectrum techniques:
– Derived from secure communications technology
– Recover a signal from below the noise level
– Susceptible to time domain modifications (wow &
flutter, resampling etc.)
– Can be combined with perceptual models
Page 13
Fraunhofer
Institut
Example of Watermark Insertion
Audio Signal
Source
Masking
Model
Watermark
Source
Modulation
Adaptive
Filter
Page 14
Fraunhofer
Institut
Watermarked
Audio Signal
Watermark testing
•
Tests have been done by
– MUSE project (coordinated by IFPI)
– 4C companies for DVD audio
– SDMI for update trigger and screening
•
Audibility tests:
– Different music has different capability to carry
watermarks without audibility
– Inaudibility needs advanced perceptual models
•
Robustness tests:
– Does the watermark survive signal modifications ?
– Does the watermark survive attempts to erase it
(malicious attacks) ?
•
Results have been positive (for SDMI criteria)
•
Malicious attacks are possible (Felten)
Page 15
Fraunhofer
Institut
Example of Watermark Detection
Audio
in
whitening
filter
bandfilter
low
pass
AGC
ejwt
FAIL
No
peak
detection
decimation
Yes
OK
Page 16
Fraunhofer
Institut
matched
filter
Watermarking for Access Control
•
Main idea: Screen all content entering the protected
domain
•
Requirements for watermark based access control:
– Needs watermark insertion on (nearly) all music
– Needs standardized watermark technology
•
Attack scenarios:
– Knowledge about the algorithm makes malicious
attacks easier
– Reissue of backlog content with watermark enables
collusion attacks (isolate the watermark from the
music)
•
The DVD video security breach (DECSS) has shown the
problem of security systems with single points of failure
Page 17
Fraunhofer
Institut
Watermarking to trace illegal copies
•
Watermark contains information about origin / distribution
information for the music
•
Use the watermark for forensic purposes only: find
watermark if tampering / illegal copying is suspected
•
No need to standardize the watermark, new technical
advances can be introduced at any time
•
No need to design the watermark for low decoding
complexity
•
Give watermark decoding technology only according to
"need to know"
•
Security is much higher than in the screening scenario
Page 18
Fraunhofer
Institut
Transactional Watermarking
•
Insert watermark "on the fly", onto the compressed
signal
•
Watermark can be detected like other watermarks
– even after D/A-A/D or signal modification
– even after another round of compression /
decompression
•
Watermark contains info on the vendor and/or customer
of an EMD transaction
•
Transactional watermarking can be done for popular
compression schemes like .mp3 or MPEG-2 Advanced
Audio Coding (AAC)
Page 19
Fraunhofer
Institut
Requirements for Successful Systems
or: what does not work ?
Page 20
Fraunhofer
Institut
Less successful systems:
•
Liquid Audio: money back to shareholders
•
a2b: no business
•
Intertrust: sold to Philips/Sony
•
IBM EMMS: used for promotion
•
Sony: got blasted by the press for SDMI conformance
•
Pressplay and the like: not really business
Page 21
Fraunhofer
Institut
Survivors:
•
Deutsche Telekom MOD
– Reappiered as popfile.de
•
Emusic, mp3.com etc.
– Not big business, but still around
•
Apple
– The first big success !
Page 22
Fraunhofer
Institut
Strategy to fight Internet Piracy
•
Education about copyright protection issues
•
Help legal distribution chains and legal applications
•
Establish a legal alternative
– seamless security
– advantages for the consumer:
access to more music, better quality, longer playing
time (possible with AAC)
•
Hunt down illegal music distribution sites.
Page 23
Fraunhofer
Institut
Requirements for successful applications:
•
Ease of use:
– work everywhere, on all equipment
= interoperability
•
Add value:
– digital is more than just the same product
add-on text / pictures / video / special sale etc.
•
Make illegal use more difficult
– enough copy protection to make piracy a conscious
decision
Page 24
Fraunhofer
Institut
User expectations
•
For
–
–
–
–
personal use, music (on Redbook CD) can be
moved (from home stereo to the car)
copied (for example to tape)
shared between family members
lent to my best friend
•
All compliant CDs play on all equipment with the same
physical form factor (interoperability)
•
Current technology (mp3) allows all of the above
•
Secure Electronic Music Distribution (EMD) has to meet
these expectations
Page 25
Fraunhofer
Institut
Who compromises security ?
Avoid piracy
via
Who are
the pirates ?
Warez scene etc. („hacker“)
Hobbiest pirates
Average people who sometimes copy
Page 26
Fraunhofer
Institut
Law enforcement
Pirates who try
to earn some money
Technical means
unauthorized
distributors
Thoughts
• Might “less than maximum security” be still
enough ?
• Isn’t usability the more deciding property of a
system ?
Our answer: YES
•
Better usability removes reasons to get around the
security measures
Page 27
Fraunhofer
Institut
Leight Weight Digital Rights Management
LWDRM®
•
A new approach:
– Look at the user requirements
– Still provide some security against unauthorized use
„Keep honest people honest“
Basic idea
•
Publishing is allowed if I show that I am responsible by
signing
•
Unsigned content stays local (only playable locally)
Page 28
Fraunhofer
Institut
Implementation
2 formats
•
Secure, locally bound content
– Bound to local equipment (PC etc.)
– Encrypted with public key
•
Signed format
– Can be played everywhere
– Encrypted using the private key of the publisher (user)
– Containes certificate of the user including public key
– Private key and certificate are provided by some certification
authority
Page 29
Fraunhofer
Institut
Properties
Open
standards
Security
•
Data format compliant to: ISO Media File Format
•
Coding: MPEG-4
•
Encryption: RSA, AES, ISMACryp
•
Does not inhibit copying, but reduces large scale unauthorized
distribution
•
Certificate contains information about the user
•
Certificate contains keys for decryption
•
Watermark as second line of defense
Page 30
Fraunhofer
Institut
Profiles of LWDRM (1/5)
Player Profile
•
Different profiles defined for replay, signing, authoring and
conversion
•
Different profiles for different requirements of users and content
providers
•
Does everything to play content according to LWDRM Inhalten
•
Needed for all equipment playing LWDRM
•
No certification of individual players necessary
Page 31
Fraunhofer
Institut
Local Profile
•
Produces content which is just locally usable (secure, bound to local
system)
•
No registration with certification authority necessary
•
This is the “test version” for new users, does not really fulfill our
usability requirements
Page 32
Fraunhofer
Institut
Signing Profile
•
Create signed format
•
Convert content from locally bound to signed (portable) format
(possibly after buying a license to do so)
•
Only possible with valid certificate from certification authority
(registration mandatory)
•
Content in signed format plays on all equipment
Page 33
Fraunhofer
Institut
B2C
Distribution
Profile
•
Secure distribution of content, this is the profile for content
providers
•
Independent of distribution chain
•
On the computer of the customer, content first is locally bound and
encrypted
•
Encryption using the public key of the target PC (PC of the
customer)
•
If allowed, conversion to signed media format (using the Signing
Profile) is possible: content then playable everywhere
Page 34
Fraunhofer
Institut
C2C
Distribution
Profile
•
Another option for users: Allows secured passing on of content
(without risk) to less trustworthy friends
•
Content is passed as locally bound to the target computer
•
Encryption using public key of the target computer
•
Conversion requires additional license from the content provider
Page 35
Fraunhofer
Institut
Summary: LightWeight DRM (LWDRM)
•
No blocking of access to files
•
Enforcement like speeding rules:
Everybody does it, but you may be caught, so people are
cautious.
•
Like license plates, you have to identify yourself
•
Done via
– Mandatory registration for tools allowing publishing
– Put info about the publisher into digital content
– Put info additionally into analog content (e.g. via
watermarking)
Page 36
Fraunhofer
Institut
Conclusions:
•
Secure distribution using traditional secure envelope
techniques faces user acceptance problems
•
Needed in the future:
– Education of customers
– Invisible security
•
One solution: do it “the other way around”
•
Less security seems to become acceptable to some in the
media industry
•
I would like to have a crystal ball:
What future is ahead ? Maximum security ?
Page 37
Fraunhofer
Institut
Sicherheit durch Lizenz (1/2)
Lizenz
•
Trägt u.a. Information über Nutzungsrecht
– Nur für privaten Gebrauch, d.h. nicht für Verteilung auf
Tauschbörsen
– Allgemeine Verteilung erlaubt
Lizenzvergabe
•
Von einem Inhalteanbieter bei Kauf eines Titels
•
Von einer zentralen Instanz für Künstler zur allgemeinen Freigabe
ihrer Titel
Page 38
Fraunhofer
Institut
Sicherheit durch Lizenz (2/2)
Auswirkung
Vorteile
•
P2P Software kann angepasst werden, dass Lizenz ausgewertet wird
•
Kein Tausch von Stücken, die nicht allgemein freigegeben sind
•
Bessere Akzeptanz von P2P Netzwerken von Seiten der
Inhalteanbieter
•
Hersteller von P2P Software müssen keine rechtlichen Maßnahmen
fürchten
Page 39
Fraunhofer
Institut
Gründe für den Einsatz von LWDRM
Für Benutzer
•
Neue Möglichkeiten und bessere Qualität
•
Berücksichtigt die Belange der Benutzer
Für Systemhersteller
Plattformunabhängig
•
Einfach und erweiterbar
Für Inhalteanbieter
•
Ermöglicht die großflächige Einführung von gesichertem Inhalt
•
Gewöhnt Benutzer an DRM durch Verwendung gemischter Inhalte
Page 40
Fraunhofer
Institut

Digital Rights Management – the other way around

Transcription

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