1. International Workshop for Technology, Economy, Social and Legal Aspects of Virtual Goods 2004, May 27-29 2004 Ilmenau, Germany Licensing Structured Data with Ease Y. W. Law, C. N. Chong, S. Etalle, P. Hartel, and R. Corin Universiteit Twente, The Netherlands chong@cs.utwente.nl

2. International Workshop for Technology, Economy, Social and Legal Aspects of Virtual Goods 2004, May 27-29 2004 Ilmenau, Germany Overview Introduction and Motivation License Script Language Why Program-based REL? Why Prolog? Licensing Model I, II, and III Conclusions and Future Work

3. International Workshop for Technology, Economy, Social and Legal Aspects of Virtual Goods 2004, May 27-29 2004 Ilmenau, Germany Introduction Digital Rights Management (DRM) is a controversial technology. We do not debate if DRM is good or bad. Here, we use our License Script, the rights expression language (REL) to license structured data.

4. International Workshop for Technology, Economy, Social and Legal Aspects of Virtual Goods 2004, May 27-29 2004 Ilmenau, Germany Motivation We are going to explain some of our design choices of License Script. We need to present several answers for the following questions: 1.Why program-based REL? 2.Why using Prolog?

5. International Workshop for Technology, Economy, Social and Legal Aspects of Virtual Goods 2004, May 27-29 2004 Ilmenau, Germany License Script 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.

6. International Workshop for Technology, Economy, Social and Legal Aspects of Virtual Goods 2004, May 27-29 2004 Ilmenau, Germany Why Program-based REL? Formal Semantics –Useful properties can be formally verified. Flexible and Highly Expressive –Able to express more novel usage scenarios.

7. International Workshop for Technology, Economy, Social and Legal Aspects of Virtual Goods 2004, May 27-29 2004 Ilmenau, Germany Why Prolog? The main component of License Script. We will show the power of Prolog in handling the structured data. We propose 3 Licensing Models using License Script that illustrates the advantages of Prolog.

8. International Workshop for Technology, Economy, Social and Legal Aspects of Virtual Goods 2004, May 27-29 2004 Ilmenau, Germany Licensing Model I Lock part of the content, to unlock needs license. Can distribute part of the content free as preview to attract users. lic(track, [canunlock(B,_,Code): get_value(B,unlockCode,U), Code==U], [unlockCode=1234]) Base License lic(track, [canplay(B,_,Code):- get_value(B,unlockCode,Code)], [unlockCode=1234]) Unlocking License play(N) : lic(N,C1,B1), lic(N,C2,B2) -> lic(N,C1,B1’), lic(N,C2,B2’) <= C2|-canunlock(B1,B1’,Code), C1|-canplay(B2,B2’,Code) Rule Play

9. International Workshop for Technology, Economy, Social and Legal Aspects of Virtual Goods 2004, May 27-29 2004 Ilmenau, Germany Combine Licensing Model II A basic set of content and bonus content which can be added on top of the basic content for free. lic(tourist_attractions, [canrender(B,_):- get_value(B,acceptAddon,A), A == 1], []) Add-on License lic(basic_map, [canrender(B,_)], [acceptAddon=1]) Basic License lic(enhanced_map, [canrender(B,_):- get_value(B,acceptAddon,A), A == 1], [acceptAddon=1]) Combined License

10. International Workshop for Technology, Economy, Social and Legal Aspects of Virtual Goods 2004, May 27-29 2004 Ilmenau, Germany Licensing Model II A basic set of content and bonus content which can be added on top of the basic content. Combine Basic License Add-on License Enhanced License

11. International Workshop for Technology, Economy, Social and Legal Aspects of Virtual Goods 2004, May 27-29 2004 Ilmenau, Germany Licensing Model II (cont’d.) 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.

12. International Workshop for Technology, Economy, Social and Legal Aspects of Virtual Goods 2004, May 27-29 2004 Ilmenau, Germany Combine Licensing Model III By using Licensing Model II, we can license the text and audio of the ebook, separately. lic(ebook, [canlisten(_,_)], [type=[audio]]) ebook-audio-part lic(ebook, [candisplay(_,_)], [type=[text]]) ebook-text-part lic(ebook, [cansynrender(_,_):- candisplay(_,_), canlisten(_,_)], [type=[text,audio]]) ebook

13. International Workshop for Technology, Economy, Social and Legal Aspects of Virtual Goods 2004, May 27-29 2004 Ilmenau, Germany Conclusions and Future Work We have provided three useful licensing schemes to use with License Script. We have shown the advantages of using Prolog in licensing. Future work – security of License Script : –To detect bad licenses. –To protect licenses confidentiality and integrity.

14. International Workshop for Technology, Economy, Social and Legal Aspects of Virtual Goods 2004, May 27-29 2004 Ilmenau, Germany Questions and Answers

15. International Workshop for Technology, Economy, Social and Legal Aspects of Virtual Goods 2004, May 27-29 2004 Ilmenau, Germany Name Conflicts Resolution Definition 1: Names Bindings, B Set of Names Head of Clauses,C Set of Names lic (Content, C, B)

16. International Workshop for Technology, Economy, Social and Legal Aspects of Virtual Goods 2004, May 27-29 2004 Ilmenau, Germany Name Conflicts Resolution Definition 2: Renaming Function Renaming Function α x X y Y z Z bijection Y ∩ Z = {} z= α(x,Y)

17. International Workshop for Technology, Economy, Social and Legal Aspects of Virtual Goods 2004, May 27-29 2004 Ilmenau, Germany Name Conflicts Resolution Definition 1: Combination l 3 is a valid license. Number of (B 3 ) = number of (B 2 ) + number of (B 1 ) Number of (C 3 ) = number of (C 1 ) + number of (C 2 ) – number of (C 1 and C 2 which has same head) lic 1 (n,C 1,B 1 ) lic 2 (n,C 2,B 2 ) lic 3 (n,C 3,B 3 ) Combine Function φ

18. International Workshop for Technology, Economy, Social and Legal Aspects of Virtual Goods 2004, May 27-29 2004 Ilmenau, Germany Name Conflicts Resolution Definition 1: Combination There exists b in C 1 and B 1 (i.e., of lic 1 ) but not in of lic 2, there exists a unique b 3 in of lic 3 then the corresponding Prolog clause in C 1 also exists in C 3. Similarly, applies to C 2 and B 2. There exists b in of lic 1 (N 1 ) and lic 2 (N 2 ), there exists unique b 3(1) and b 3(2), b 3(1) ≠ b 3(2) such that b 3(1) = α 1 (b, N 1 U N 2 ) and b 3(2) = α 2 (b, N 1 U N 2 ), then the clause b:- b 3(1),b 3(2) in of lic 3