Guarding a Walled Garden - Semantic Privacy Preferences for the Social Web Philipp Kärger and Wolf Siberski L3S Research Center, Hannover, Germany Philipp Kärger - L3S Research Center 05/05/19

Outline Observations and Problem Statement A Unified Privacy Model Implementation using OpenSocial Future Work and Conclusions Philipp Kärger - L3S Research Center 05/05/19

Observations and Problem Statement Philipp Kärger - L3S Research Center 05/05/19

Privacy Decisions: who and what Who is requesting? Do I know the guy? Did I ever meet him? Did I ever talk to him? Is he a colleague? Didn’t I meet him at ESWC? What is requested? Is the requested thing/action private? Do I want to share the requested thing? Isn't it the picture I took once at this nice ESWC talk? Philipp Kärger - L3S Research Center 05/05/19

The Who and the What reflected on the Social Web: Philipp Kärger - L3S Research Center 05/05/19

But what about … … the social context? You are allowed if you … posted in my forum. are my friend in either Facebook or Skype. are in one of my Orkut groups. are in any of my Flickr pictures. attended ESWC. like the same music. are interested in Semantic Web. are listed in my FOAF profile. … the social context? Philipp Kärger - L3S Research Center 05/05/19

Privacy Preferences are Trapped Platforms share similar concepts like friends groups messages and chats profile information blocked users shared resources But privacy preferences cannot be exported and reused. Philipp Kärger - L3S Research Center 05/05/19

Summary: Motivation Privacy Preferences on the Social Web are restricted to predefined categories (fixed Whos and Whats) cannot refer to social context - although it is available (Walled Garden No. 1) cannot be exported and reused crossing platforms (Walled Garden No. 2) Philipp Kärger - L3S Research Center 05/05/19

A Unified Model for Privacy Preferences Philipp Kärger - L3S Research Center 05/05/19

“Somebody is allowed to do/see something.” A Privacy Preference is a mapping from What to Who Set of actions/objects to Set of persons Object category to Subject category Philipp Kärger - L3S Research Center 05/05/19

Object and Subject Categories users shall be allowed to define new subject categories e.g., “A family member is every person who is in my FOAF profile or in my Facebook group ‘family’.” family_member(X) :- foafFriend(X) ; inFacebookGroup(X,’family’). new object categories e.g., “A party picture is everything which is a picture and tagged with ‘party’.” party_picture(X) :- picture(X) , taggedWith(X,’party’). Philipp Kärger - L3S Research Center 05/05/19

And-Or-Tree visualization of categories Object Categories – the “What” Subject Categories – the “Who” Philipp Kärger - L3S Research Center 05/05/19

User-defined Mappings on Categories also explain enforcement enforcement happens acc. to the Mappings common vocabulary  unified format Philipp Kärger - L3S Research Center 05/05/19

Summary new categories can be defined by rules party_picture(X) :- picture(X) , taggedWith(X,’party’). mappings between these categories define privacy preferences Every party_picture can be accessed by every friend. platform independent when exploiting a suitable vocabulary Philipp Kärger - L3S Research Center 05/05/19

Implementation Philipp Kärger - L3S Research Center 05/05/19

Goals a uniform representation of Privacy Preferences  RDF extend standard Social Web platform to enforce such preferences  the OpenSocial Implementation Apache Shindig support the integration of arbitrary social contexts for the preferences  Policy Engine “Protune” plus Social Web wrapper Philipp Kärger - L3S Research Center 05/05/19

Apache Shindig – an Open Social Implementation Open Social – an API for Social Web sites defining methods for retrieving personal information (profile data) getting activity notification storing/retrieving application data sending/receiving messages Apache Shindig container for hosting Social Web applications implements Open Social API basis to easily develop Social Web platforms Philipp Kärger - L3S Research Center 05/05/19

Shindig Extension filters requests (Open Social API calls) for information about persons interprets our Privacy Preference Model Protune is used as policy engine for privacy enforcement privacy enforcement calls external sources  used to check social context family_member(X) :- foafFriend(X) ; inFacebookGroup(X,’family’). Philipp Kärger - L3S Research Center 05/05/19

Philipp Kärger - L3S Research Center 05/05/19

Social Context Privacy Preferences can relate to arbitrary RDF sources, e.g., FOAF, SIOC, DOAP relationships on Twitter friendships on Flickr any OpenSocial information (e.g., age, current location, address) co-authorship on DBLP (via the DBLP SPARQL endpoint) Philipp Kärger - L3S Research Center 05/05/19

Implementation Summary each Shindig-based platform can adopt it reuse and share RDF format of Privacy Preferences integrate of social context gathered from the Web Philipp Kärger - L3S Research Center 05/05/19

Future Work & Conclusions Philipp Kärger - L3S Research Center 05/05/19

Future Work Authentication and identification User Interface FOAF+SSL OpenID certificates, credentials, Trust Negotiation User Interface Philipp Kärger - L3S Research Center 05/05/19

Philipp Kärger - L3S Research Center 05/05/19

Conclusions Social Web Privacy Preferences share a simple scheme are limited to concepts of one platform only are not portable to other platforms We introduced a new Privacy Preference Model easily extendable with complex categories crosses the Walled Garden Our Implementation exploits OpenSocial and Protune uses RDF representation of Privacy Preferences Philipp Kärger - L3S Research Center 05/05/19

Thanks for your attention. Philipp Kärger L3S Research Center kaerger@L3S.de www.L3S.de/~kaerger Philipp Kärger - L3S Research Center 05/05/19