Licensing Structured Data with Ease

1
Licensing Structured Data with Ease

• Y. W. Law, C. N. Chong, S. Etalle,
• P. Hartel, and R. Corin
• Universiteit Twente, The Netherlands
• chong_at_cs.utwente.nl

2
Overview

• Introduction and Motivation
• LicenseScript Language
• Why Program-based REL?
• Why Prolog?
• Licensing Model I, II, and III
• Conclusions and Future Work

3
Introduction

• Digital Rights Management (DRM) is a
  controversial technology.
• We do not debate if DRM is good or bad.
• Here, we use our LicenseScript, the rights
  expression language (REL) to license structured
  data.

4
Motivation

• We are going to explain some of our design
  choices of LicenseScript.
• We need to present several answers for the
  following questions
• Why program-based REL?
• Why using Prolog?

5
LicenseScript Language

• License consists of three parts content,
  clauses, and bindings.
• Clause is a Prolog program to decide if the
  operation is allowed.
• Bindings store license data.
• Rule can be thought of as firmware of a system.

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Why Program-based REL?

• Formal Semantics
• Useful properties can be formally verified.
• Flexible and Highly Expressive
• Able to express more novel usage scenarios.

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Why Prolog?

• The main component of LicenseScript.
• We will show the power of Prolog in handling the
  structured data.
• We propose 3 Licensing Models using LicenseScript
  that illustrates the advantages of Prolog.

8
Licensing Model I
Play

• Lock part of the content, to unlock needs
  license.
• Can distribute part of the content free as
  preview to attract users.

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Licensing Model II

• A basic set of content and bonus content which
  can be added on top of the basic content for free.

Combine
10
Licensing Model II

• A basic set of content and bonus content which
  can be added on top of the basic content.

Combine
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Licensing Model II (contd.)

• We have given a formalism of the combination
  operation.
• We have defined a formalism to resolve the
  potential name conflicts at clauses and bindings.
• Content providers can have more flexible
  licensing to their structural data.

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Licensing Model III

• By using Licensing Model II, we can license the
  text and audio of the ebook, separately.

Combine
13
Conclusions and Future Work

• We have provided three useful licensing schemes
  to use with LicenseScript.
• We have shown the advantages of using Prolog in
  licensing.
• Future work security of LicenseScript
• To detect bad licenses.
• To protect licenses confidentiality and
  integrity.

14
Questions and Answers
15
Name Conflicts Resolution Definition 1 Names
lic (Content, C, B)
Bindings, B Set of Names
Head of Clauses,C Set of Names
16
Name Conflicts Resolution Definition 2 Renaming
Function
Renaming Function a
bijection
Y n Z
z a(x,Y)
17
Name Conflicts Resolution Definition 1
Combination
Combine Function f
lic1(n,C1,B1)
lic3(n,C3,B3)
lic2(n,C2,B2)

• l3 is a valid license.
• Number of (B3) number of (B2) number of (B1)
• Number of (C3) number of (C1) number of (C2)
  number of (C1 and C2 which has same head)

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Name Conflicts Resolution Definition 1
Combination

• There exists b in C1 and B1 (i.e., of lic1) but
  not in of lic2, there exists a unique b3 in of
  lic3 then the corresponding Prolog clause in C1
  also exists in C3.
• Similarly, applies to C2 and B2.
• There exists b in of lic1 (N1) and lic2 (N2),
  there exists unique b3(1) and b3(2), b3(1) ?
  b3(2) such that b3(1) a1(b, N1U N2) and b3(2)
  a2(b, N1U N2), then the clause b- b3(1),b3(2)
  in of lic3