25/10/2009Philipp Kärger1 Reactivity and Social Data: Keys to Drive Privacy Decisions in Social Network Applications* * This work was partially supported.

25/10/2009Philipp Kärger 1

Reactivity and Social Data: Keys to Drive Privacy Decisions in Social Network Applications*

* This work was partially supported by the FP7 EU Project OKKAM (contract no. ICT-215032)

Philipp Kärger1, Emily Kigel1, Daniel Olmedilla2

1L3S Research Center2Telefonica Research & Development, Madrid, Spain

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Outline

1.MotivationPrivacy settings on the Social Web

2.BackgroundSemantic Web policies

3.Reactivity and Social Data Defining Social Concepts in Semantic Web policies A reactive policy language

4.Implementation

5.Prototype Reactive Social Web policies in Skype

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Motivation

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How do we make privacy decisions?

• do I know this guy?• did I ever talk to this guy?• did I ever meet this guy?

• is the requested thing private?• do I want to share the requested thing?

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Social context?

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… if you are

posting in my forum.

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… if you are

listening to the same music.

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… if you are

working for the same company.

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… if you are

participating in the same OpenSource project.

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… if you are

in regular email contact with me.

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… if you are

my friend on Facebook.

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What is the result of a privacy decision?

• yes, you can see it but …• yes, you can talk to me but only 10 minutes• yes, you can call me but not on the mobile phone• no, but you can send me an email

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Observations

Privacy decisions are not so simple …

• they depend on the Social context the requester the requested action

• results are not just “allow/deny” but reactions limited requests

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Privacy Settings on the Social Web• closed world (“walled garden”)

what actually influences privacy decisions?

• static no reaction, just allow and deny

• no inclusion of strong evidences

• no inclusion of weak evidences

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Semantic Web Policies

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Semantic Web policies

A policy is “a (declarative) description of the behavior of a system”.

Semantic Web policies:• have a well define semantics• incorporate information from difference knowledge sources• gained a lot of research effort in the last years• several policy frameworks and policy languages are

available

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Semantic Web policies - Features

Privacy statements can be changed/updated without re-coding, re-compiling, re-installing, etc.

in a costless manner

Reasoning on privacy statements Generation of explanations Reusability Extensibility Context-sensitivity Verifiability

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allow(access(Picture, Requester)) isTagged(Picture,”iswc2009”),isMemberOfGroup(Requester,”iswc2009”).

isMemberOfGroup(Person, “iswc2009”) isMemberInFacebookGroup(Person,“iswc09”).

isMemberOfGroup(Person, “iswc2009”) hasInterest(Person,“Semantic Web”).

Semantic Web Policies incorporating Social Data

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isMemberOfGroup(Person, “iswc2009”) hasPostedOnMySemWebBlog(Person).

isMemberOfGroup(Person, “iswc2009”) isMyCoAuthor(Person, Conference, Year),Conference = “ISWC”.

isMemberOfGroup(Person, “iswc2009”) providesCredential(Person, Credential),Credential.issuer = “W3C_SemanticWeb_Group”.

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A Reactive Policy Language

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A Reactive Policy

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Implementation

Social Web

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SPoX – Driving the behavior of Skype

- Skype Policy Extension

- Reactive policies define - who is allowed to do what- which notification shows up

- Social data can be used asconditions in the policies.

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Defining a reactive policy in SPoX

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SPOX

• Don’t miss the Demo at ISWC’s Demo Session

• Screencast + Downloads at

www.L3S.de/~kaerger/SPoX

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Open issues, future work

• the challenge of identificationmatching (identifying properties?)platform crossing identification (OpenID, FOAF+SSL, keys)

• integration of other social platforms which other data is useful for the social context

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Conclusions

• privacy preferences require social context social context is availablewe exploited it for privacy policies

• privacy preferences include reactionssuch as “you are allowed but only …”we developed a reactive policy language

• implementation as extension to Protune• application as policy control for Skype