1. CONTENT PROTECTION AND DIGITAL RIGHTS MANAGMENT

2. What is missing? WHAT IS MISSING IN THIS PICTURE?
Here we see scheme of networked multimedia system, red part is
hardware, blue is content, green is software for running it.
WHAT IS MISSING IN THIS PICTURE?
The missing part is CONTENT PROTECTION AND DRM

3. DIGITAL CONTENT (AUDIO,
VIDEO, GRAPHICS, IMAGES)
CAN BE EASILY COPIED, TRANSMITTED AND DISTRIBUTED
THIS HAS GREAT ADVANTAGES AND
BUSINESS POTENTIAL

4. BUT DIGITAL MEDIA CAN ALSO MAKE BIG PROBLEMS FOR CONTENT OWNERS DUE TO UNAUTHORIZED USE. THEY CAN EASILY LOSE THEIR PROPERTY
CONTENT OWNERS NEED THUS STRONG PROTECTION

5. THUS DIGITAL CONTENT SHOULD
BE PROTECTED AGAINST
UNAUTHORIZED USE
THIS PROBLEM IS KNOWN CURRENTLY
UNDER THE NAME DRM
DIGITAL
RIGHTS
MANAGEMENT

6. Digital Rights Management (DRM)
= technologies used by publishers or copyright owners to control access to or usage of digital data or hardware, and to restrictions associated with a specific instance of a digital work or device
can be used
to protect high-value digital assets
control their distribution and usage
Ultimate goal:
persistent content protection against unauthorized access to the digital content, limiting access to only those with the proper authorization
to manage usage rights for different kinds of digital content (e.g.music files, video streams, digital books, images)
different platforms (e.g. PCs, laptops, PDAs, mobile phones)
control access to content delivered on physical media or any other distribution method (e.g., CD-ROMs, DVDs)
Essential to the content whuch production requires huge amount of money, but can be copied in a second

7. Digital Rights Management (DRM)
Different methods for
Audio
Video
Internet stores
Documents (Enterprise DRM)
Digital licenses
the consumer purchases a license with certain rights
A license is a digital data file that specifies certain usage rules (frequency of access,expiration date, restriction of transfer to other devices, copy permission etc., may combined to try-before-buy) for the digital content
Several players involved in
E.g. online distribution:
content provider, distributor,
consumer, clearing house
DVD’s manufacturer, replicator, player…
Consumer: privacy, fair use (research, education..), usability (compatibility, seamless, updates)
Essential to the content whuch production requires huge amount of money, but can be copied in a second

8. EXAMPLE: Apple music store
Buying music from the
network means that the
content has to be protected
against copying

9. WHAT ARE THE REQUIREMENTS FOR DRM?
IT SHOULD PREVENT COPYING
IT SHOULD AUTHORIZE ACCESS
LIMITED TO: PARTICULAR USER,
SPECIFIC TIME, SPECIFIC NUMBER
USAGE AND COPIES, ETC.
IT SHOULD FACILITATE PAYMENT
FOR CONTENT (E.G. RENEWAL OF
RIGHTS)

10. ALL REQUIREMENTS FOR DRM ARE VERY DIFFICULT TO SATISFY
IN PARTICULAR THEY ARE DIFFICULT IF THE DRM SYSTEM WOULD BE STANDARDIZED, THAT IS
IS STRUCTURE IS KNOWN
THIS IS BECAUSE STANDARDIZED SYSTEM MIGHT BE EASIER TO BREAK THAN SECRET SYSTEM

11. IN PRINICPLE DIGITAL CONTENT CAN BE EASILY (?) PROTECTED
BY ENCRYPTION
WHAT IS ENCRYPTION?
THE CONTENT BITS ARE MANIPULATED IN SECRET WAY
BY SOME ALOGRITHM.

12. THE ORIGINAL BITS CAN BE RECOVERED BY REVERSING THE OPERATION OF THE
ALGORITHM
CONTENT
ENCRYPTION
ALGORITHM
DECRYPTION
ALGORITHM
CONTENT

13. BUT SUCH SYSTEM HAS PROBLEMS
IF ALGORITHM IS KNOWN,
EVERYBODY WILL USE IT
HOW TO CONTROL ACCESS?
THAT IS USERS MAY BUY ACCESS
FOR SOME TIME AND FOR SOME
CONTENT ONLY
WHAT TO DO WITH USERS WHICH
WILL USE PROPER ACCESS FOR
ILLEGAL COPYING?

14. THUS THE DRM CONTENT PROTECTION MUST BE MORE CLEVER IT HAS TO BE BASED ON
CONDITIONAL ACCESS
ENCRYPTION ALGORITHMS
and the newest addition is:
3. REVOCATION OF RIGHTS

15. WHAT IS CONDITIONAL ACCESS? IT IS ACCESS GIVEN ON LIMITED
CONDITIONS, E.G. TIME, CONTENT,
PAYMENT
CONDITIONAL ACCESS
CONTENT
ENCRYPTION
ALGORITHM
DECRYPTION
ALGORITHM
CONDITIONAL ACCESS CAN BE A CARD GIVEN
TO THE USER, OR CERTIFICATE SEND VIA
INTERNET

16. EXAMPLE – THE SYSTEM USED IN
DIGITAL TELEVISION FOR WATCHING PAY PROGRAMS
IN THIS SYSTEM CA HAS A FORM
OF SUBSCRIPTION CARDS
HOWEVER, THERE ARE SEVERAL
ENCRYPTION ALGORITHMS USED.
FOR DECRYPTION, THERE ARE
DIFFERENT HARDWARE CAM’s
CONDITIONAL ACCESS MODULES

17. RECEIVER FOR DIGITAL TELEVISION
SUBSCRIPTION CARD
CAM MODULE

18. ONE RECEIVER CAN HAVE SEVERAL CAM’s FOR RECEIVING
PAY PACKAGES WITH DIFFERENT
SUBSCRIPTION CARDS. SUCH SYSTEMS ARE WIDELY USED IN TELEVISION.
BUT MANY SYSTEMS WERE ALSO
BROKEN SINCE ONE CAN ANALYZE
PROGRAM ON THE CARD AND TRACE TRAFFIC BETWEEN
CARD AND CAM.

19. BUT WHAT TO DO IF A USER HAS
VALID SUBSCRIPTION BUT USES
IT FOR RECORDING AND DISTRIBUTING CONTENT ILLEGALLY?
ONE SOLUTION IS TO PREVENT
RECORDING AND/OR TO PREVENT
GETTING THE RECORDING OUT
OF THE DEVICE

20. IN MEDIA TERMINAL USER CAN
RECORD DIGITAL TV PROGRAMS
ON INTERNAL HARD DISC
BUT RECORDED CONTENT IS
ENCRYPTED AND THERE IS NO
WAY OF GETTING IT OUT OF THE
TERMINAL

21. REVOCATION OF RIGHTS
Revocation means that grants given once
are removed from the user who breached the contract.
We shall explain revocation on the new
example of High Definition DVD discs

22. Current DRM systems for DVD
Legacy Format
Advanced Format
Standard Definition
High Definition
CSS
= Content Scramble System
AACS
= Advanced Access Content System
DVD
HD DVD
Blu-ray Disc
Other
formats
OTHER FORMATS:
- FOR AUDIO: Pre-recorded audio CPPM (56-bit key)
DVD Content
Protection is
broken
HD DVD is a new system with much
improved protection and REVOCATION

23. Content Scramble System (CSS) Protection for DVD
A data encryption and authentication scheme to prevent copying video files from the disks
Several keys included in: authentication key, disc key, player key, title key, second disk key set, and/or encrypted key
a weak 40-bit stream cipher algorithm
Brute Force Attact, possible to find the keys, only 2^40 options, attacts to the hash codes
Published 1996, but only usable in licensed DVD playbacks (Windows, MAC), not in Linux
 1999 DeCSS

24. Advanced Access Content System (AACS) for HD DVD
= a standard for content distribution and digital rights management, intended to restrict access to and copying of the next generation of optical discs and DVDs.
“ a specification for managing content stored on the next generation of prerecorded and recorded optical media for consumer use with PCs and CE devices. “
“will complement new innovations in the next-generation of optical discs, and enable consumers to enjoy next-generation content, including high-definition content.”
The specification released in April 2005
In addition to the general objectives described in the Introduction and Common Cryptographic Elements book
of this specification, the use of AACS for protecting pre-recorded video content was designed to meet the
following specific criteria:
• Provide robust protection for both off-line playback and optional enhanced uses enabled via on-line
connection.
• Provide for extended and extensible usage (e.g. jukebox storage, pay for copy).
• Independent of physical storage format to the degree possible.
• Compliant players can authenticate that content came from an authorized, licensed replicator.
AACS is designed to meet the following general criteria:
• Meet the content owners’ requirements for robustness and system renewability
o Content encryption based on a published cryptographic algorithm.
o Limit access to protected content to only licensed compliant implementations.
o Support revocation of individual compromised devices’ keys.
o Limit output and recording of protected content to a list of approved methods.
• Suitable for implementation on both general-purpose computer and fixed-function consumer
electronics platforms.
• Applicable to both audio and video content, including high-definition video.
• Applicable to various optical media formats.
• Transparent to authorized use by consumers.
To meet these general objectives, AACS is based in part on the following technical elements:
• Robust encryption of protected content using the AES cipher.
• Key management and revocation using advanced Media Key Block technology.

25. AACS – Design criteria
Meet the content owners’ requirements for robustness and system renewability
Content encryption based on a published cryptographic algorithm.
Limit access to protected content to only licensed compliant implementations.
Support revocation of individual compromised devices’ keys.
Suitable for implementation on both general-purpose computer and fixed-function consumer electronics platforms.
• Applicable to both audio and video content, including high-definition video.
• Applicable to various optical media formats.
• Transparent to authorized use by consumers.
Basic technical elements:
Robust encryption of protected content using the AES cipher.
Key management and revocation using advanced Media Key Block technology.

26. AACS - Usage Scenarios Compared to CSS: + Legal copies
+fexibility to use

27. AACS : Content validation and revocation
Content Owner
Content Owner
Licenced Player
Licensed Players will contain the Entity Public Keys that will be used as the root of trust for validating content
signatures. Media containing content signed in accordance with this scheme will contain the following items:
• Content Certificate
• Content Hash Table
• Content Revocation List
The Content Certificate and Content Hash Table
 Validate the the authenticity of the content
 prevent playback of that content if the signature is not valid.
The Content Revocation List
 prevent playback of content that contains a valid signature but is not valid content.
The Content Certificate, Content Hash Table, and Content Revocation List must be stored on the pre-recorded
media with the signed content.
Licensed replicators shall include with any Certified Content that they produce, a signed Content Certificate
covering that content.
Licensing Entity

28. AACS: System overview – pre-recorded video
CONTENT OWNER
SERVCE PROVIDER
Content
Usage rules
Enhanced uses enabled via
online authentication
PRE-RECORDED VIDEO
Title keys
- Encrypted content
- Usage rules of content
Content certificate
Conten hash
Device revocation data [MKB]
Content revocation list [CRL]
Sequence key block
LICENCED REPLICATOR
LICENCED PLAYER
Device revocation data
[MEDIA KEY BLOCK]
Content revocatio list [CRL]
Content sertificate
Sequence Key Block
Secret keys
Device keys
(unique for the device /application)
Entity public keys
(to check the content revocation data and content sertificate)
CONTENT OWNER:
+ provides AV content
+ usage rules
+ title keys
LICENSING ENTITY  LICENCED REPLICATOR
+ DEVICE REVOCATION DATA = MEDIA KEY BLOCK
+ MKB enable players using own device keys to calculate the MEDIA KEY
+ If the keys hackered ´the old keys can be revoked by new MEDIA KEY BLOCK
+ CONTENT REVOCATION LIST
= identifies the sign content with valid certificate,
but has later on revoked and should not be accessed by compliant player
+ CONTENT SERTIFICATE
= for content identifying, including cryptographic hash collection
+ SEQUENCE KEY BLOCK
+ SECRET KEYS based on device variation and media key
LICENCED REPLICATOR
+ encrypts the content
+ TITLE KEY – content with media key information
- contains the USAGE RULES OF THE CONTENT
 uses several secret keys  called TITLE KEYS (for playback you need to know several title keys)
Media keys differes between the movies a lot
+ all other information stored on storage medium
LICENSING ENTITY  LICENCED PLAYER
+ DEVICE KEYS (unique for devices and applications)
- needed to encrypt the device revocation data
+ ENTITY PUBLIC KEYS
 used to check the CONTENT REVOCATION DATA and CONTENT CERTIFICATE
PLAYER
+ uses DEVICE KEYS to check the compatibility to MEDIA KEY BLOCK, to calkulate media key form media key block
+ based on MEDIA KEY + SEQUENCE KEYS  SKB (Sequence Key Block)  Media key variant
+ TITLE KEY to check to provide the compliant playback
+ CRL
+ compliant player keeps the CRL in non-volatile storage, unless it already has a more up-to-date list.
+ Using the most up-to-date CRL, the player checks to see if the content is revoked, and if it is, access is aborted.
+ During playback, the compliant player calculates a series of content hashes using the same method used by the
replicator. Replicators and player’s hashs needs to match.
ENHANCED USES ENABLED VIS ONLINE AUTHENTICATION
+ For example, a home video server might connect with a service provider to obtain authorization to make a protected local copy of a given pre-recorded Title for “jukebox”
purposes.
- authorization  free-of-charge to the owner of the optical media
- Thus, this and other enhanced uses may entail business
interaction between content owners and service providers, as indicated by the dashed line in the figure above.
LICENSING ENTITY

29. AACS: Content encryption and decryption

30. AACS: Revoking the keys – in practice
In practice the operation of revocation in AACS is as follows:
- Each content (e.g. movie disc) release gets special key
Each type of player (hardware and software) gets special key
Now let’s think that somebody has broken protection of this
movie disc and released illegal copies or has modified player so
it can play illegally the content.
Then those discs and players will be put on the revocation list.
The list is updated on all new discs, so the when new disc is
played on the player, playback of the broken disc will be disabled
or the player is disabled!
+ IN FEB. 128-bit string of handful numbers and digits was published on websites
 The websites were ask to be taken off  now in you tube in T-shirts
+ Just one of the several needed keys, but it compromises the part of AACS
UNIQUE MACHINE SPECIFIC KEYS OF HW COMPANIES  USED FOR PLAYERS
COMMON KEYS FOR THE SOFTWARE  CAN BE USED IN EVERY COPY OF THE PROGRAM VERSION
THE RELEASED key was a COMMON KEY FROM Cyberlink corp and Intervideo
AACS ASKED
1. SOFWARE COMPANIES TO REVOKE THE RELEASED KEY IN 2 WEEKS
- Lots of work. E.g. PC stores have lots of PC’s and Laptop’s where the programs are installed as default
2. NEW MEDIA KEY BLOCK for HD DVD MANUFACTURERS
 New disks on markets this month
 Customers not able to play any disks released after may 2007 until the sofware versions are released
THERE MIGHT BE CUSTOMERS SAYING THAT THEIR CD DOES NOT PLAY

31. AACS: Revoking the keys – in practice
Feb bit string of keys was published
Compromises the part of AACS
Common keys for software players (Cyberlink, Intervideo)
Revocation started
HD DVD’s with New Media Block’s on markets in May
 Customers not able to play any disks released after may 2007 until the sofware versions are released
- Sofware updates = lots of work, not available yet?
+ IN FEB. 128-bit string of handful numbers and digits was published on websites
 The websites were ask to be taken off  now in you tube in T-shirts
+ Just one of the several needed keys, but it compromises the part of AACS
UNIQUE MACHINE SPECIFIC KEYS OF HW COMPANIES  USED FOR PLAYERS
COMMON KEYS FOR THE SOFTWARE  CAN BE USED IN EVERY COPY OF THE PROGRAM VERSION
THE RELEASED key was a COMMON KEY FROM Cyberlink corp and Intervideo
AACS ASKED
1. SOFWARE COMPANIES TO REVOKE THE RELEASED KEY IN 2 WEEKS
- Lots of work. E.g. PC stores have lots of PC’s and Laptop’s where the programs are installed as default
2. NEW MEDIA KEY BLOCK for HD DVD MANUFACTURERS
 New disks on markets this month
 Customers not able to play any disks released after may 2007 until the sofware versions are released
THERE MIGHT BE CUSTOMERS SAYING THAT THEIR CD DOES NOT PLAY
RESPONSE TO REPORTS OF ATTACKS ON AACS TECHNOLOGY
April 16, AACS LA Announces Security Updates (Updated URLs)
In response to attacks against certain PC-based applications for playing HD DVD and Blu-ray movie discs, Advanced Access Content System Licensing Administrator, LLC (“AACS LA”) announces that it has taken action, in cooperation with relevant manufacturers, to expire the encryption keys associated with the specific implementations of AACS-enabled software.
Consumers can continue to enjoy content that is protected by the AACS technology by refreshing the encryption keys associated with their HD DVD and Blu-ray software players. This refresh process is accomplished via a straightforward online update.
Through this online update process, manufacturers are also able to see that consumers update their player implementations prior to distribution of encryption key expiration information via new movie discs.
Consumers are advised to check with the manufacturer of their AACS-enabled Blu-ray or HD DVD PC-based player to make sure you have installed the latest version. The following manufacturers have provided links to provide relevant information and facilitate consumer updating of their players:
InterVideo – publishers of WinDVD products
CyberLink – publishers of PowerDVD products
February 15, 2007
Regarding the reported attacks on 2/13/2007, AACS has confirmed that an additional key (called a “processing key”) has been published on public websites without authorization. This is a variation of the previously reported attack (a compromise of a specific implementation) on one or more players sold by AACS licensees. Although a different key was extracted, this represents no adverse impact on the ability of the AACS ecosystem to address the attack. All technical and legal measures applicable to the previously reported attack will be applicable against this attack as well.

32. Summary
DMR
= technologies used by publishers or copyright owners to control access to or usage of digital data or hardware, and to restrictions associated with a specific instance of a digital work or device
to protect high-value digital assets
control their distribution and usage
AACS
Cross-industry collaboration to facilitate next generation content distribution
Enables new, flexible ways to enjoy content while protecting copyrighted works
Technical specifications and licensing
RELEASE OF KEYS IN FEB 2007
+ On websites  AACS players put down
+ YouTube
+ a "processing key," an 128-bit string represented by a handful of numbers and digits.
+ By itself an individual processing key is no major threat.
+ It is just one of several keys needed as part of a cryptographic process to unlock content on an HD DVD or Blu-Ray HD disk.
+ Nevertheless, the public release of a key does compromise part of a system developed by the Advanced Access Content System (AACS),
+ a consortium of content and systems companies that defined the security for HD disks.
+ Once the key was in the clear, AACS started a process of revoking it.
TWO TYPE OF KEYS:
+ Unique keys  hardware companies to use in HD players, belongs to spesific machine
+ Common keys  software players to be used in the every copy of a program of the given version
+ keys on HD disks
In cryptographic process all these keys are used to unlock the content on a disk.
THE RELEASED KEYS WERE COMMON KEYS SOFTWARE COMPANIES, CyberLink Corp. And InterVideo
AACS  RELESED KEYS TO BE REVOKED
+ new versions of software has to be released in two weeks with new keys!
+ software companies (Cyberlink and Intervideo) need to inform
+ their partners e.g. their sofwares as default softwares in Samsung’s PC’s
NEW MEDIA KEY BLOCK released to HD disk manufacturers
+ new key blocks avalable in May
+ people can still use the keys to access the content form the disk printed before may 2007
SOFTWARE UPDATE
+ Updates may not been released  products on the market chich cannot play the disks thhat has new Media key block, released in this month
+ the process is an imperfect one and some users may not discover the problem until they put in a new HD disk and see the screen go blank.
"There's a whole eco-system of content owners, software companies, PC makers and consumer here,"