Controlled Sharing of Personal Content using Digital Rights Management

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Controlled Sharing of Personal Content using
Digital Rights Management

• Claudine Conrado, Milan Petkovic, Michiel van der
  Veen and Wytse van der Velde
• ISS Department, Philips Research
• Eindhoven, The Netherlands

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Overview

• Digital content distribution
• Digital Rights Management (DRM)
• Extended DRM for personal content
• Components and architecture
• Content protection
• Content sharing
• Registration of content
• Private ownership of content
• Conclusions

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Digital content distribution

• Digital content distribution is an emerging
  business for commercial content providers
• So commercial content distribution requires
  measures to prevent illegal content distribution
• Digital Rights Management
• Technology providing content protection by
  enforcing the use of digital content according to
  granted rights

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Digital content distribution

• Trend digital personal content nowadays is
  produced in large scales by users
• Personal content
• requires distribution and management tools, and
• it is usually (very) private
• Controlled sharing of personal content Reuse
  (concepts of) a commercial DRM

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Extended commercial DRM

• Requirements
• It is essential that the commercial DRM system
  security is not compromised
• Given the security requirements, the privacy of
  users should be preserved as much as possible

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A DRM system for commercial and personal content
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Extended DRM for personal content

• DRM main components

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Extended DRM for personal content

• Certificate Hierarchy

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Content protection and sharing
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Content protection
Usually the users device
User who owns the content
1. User A authenticates with the compliant device
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Content protection
2. The compliant device creates the content
container, the Content Right and User Right for
user A.
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Content sharing
Device where content is accessed
3. A compliant device obtains the relevant
certificates as well as the content container.
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Content sharing
User who is given the right to access the content
4. User B authenticates with the compliant device.
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Content sharing
5. The compliant device checks all certificates
before giving user B access to the content.
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How is content registered?
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Content registration

• Goals of registration
• to securely establish content ownership (so that
  the user can act as content provider of her own
  content)
• to check the content (to prevent that a user
  introduces in the system illegal content, i.e.,
  content that does not belong to her)

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Content registration
1. The user imports the content into her
compliant device, which calculates the content
fingerprint.
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Content registration
2. The compliant device provides the Service
Provider Authority (SPA) with the content
fingerprint and users identity.
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Content registration
3. The SPA matches the fingerprint against a
database of fingerprints of known commercial and
registered personal content.
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Content registration
A watermark identifier may be optionally
generated.

• 4. When there is no match, the SPA generates
• a database entry linking the user and the
  content, and
• a Content ID Certificate.

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Content registration
5. The SPA sends the Content ID Certificate (and
the watermark identifier, if used) to the
compliant device.
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Content registration
When watermarks are used, the device embeds the
watermark identifier into the content.
6. Finally, all necessary certificates are
created to make the content suitable for
distribution in the DRM system.
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Content registration

• Security against import of illegal content
• Fingerprint check prevents a user from
  introducing known content into the system
• DRM infrastructure allows tracking of a
  dishonest user who distributes the content
• Watermark extraction allows forensic tracking
  outside the DRM system

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And what about the users privacy?
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Private content ownership

• Pseudonyms content registration
• A user may register content so that there is no
  link between her real identity and the content
• The user may also require that all her content
  items cannot be linked to one another
• Controlled anonymity the user is anonymous
  towards all parties, except the SPA

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Pseudonymous content registration

• Assume a cryptographic system where the
  public/private key pair is built as
• the private key is x , and
• the public key is h gx ,
• where g is a group generator in that system
• The SPA generates a different public key h (a
  new pseudonym) for each piece of content
  registered by the user by
• choosing a random value a , and
• calculating h ha, with the new private key
  being x xa

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Pseudonymous content registration

• When there is no match in fingerprints, the SPA
• generates the random value a ,
• computes the users pseudonym h
• h gt Content ID Cert
• a gt database entry

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Pseudonymous content registration

• The SPA sends to the compliant device
• the Content ID Certificate,
• the random value a

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Pseudonymous content registration

• Content is anonymously introduced into the DRM
  system
• h content providers identity
• However, the user is still accountable via the
  SPA

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Concluding..
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Conclusions

• Commercial DRM system is extended to handle also
  personal content, allowing users to controllably
  share their content
• Content registration is performed to establish
  content ownership and prevent illegal import of
  content
• Users may remain anonymous in the system, but
  anonymity is revocable gt likely to be a
  requirement on the part of commercial content
  providers

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