Semantic Web Technologies to
Reconcile Privacy and Context
Awareness
Norman M. Sadeh
ISRI- School of Computer Science
Carnegie Mellon University
Pittsburgh, PA - USA
Copyright ©2001-2004 Norman Sadeh
Mobility Challenge
Can no longer assume the user’s undivided
attention
 Time critical nature of many tasks
 Limited input/output functionality

Copyright ©2001-2004 Norman Sadeh
Context Awareness

…All this argues for:
 Higher levels of automation
 Context awareness
 …True also in fixed Internet scenarios
Copyright ©2001-2004 Norman Sadeh
Sources of Contextual Information


A user’s context information is distributed across a
number of disparate resources
 Calendar
 Location tracking
 Address book
 Buddy lists
 Weather
Available resources vary from one user to another
 …and over time
 e.g. roaming across different networks
Copyright ©2001-2004 Norman Sadeh
Vision

A growing collection of context-aware agents that
users can buy or subscribe to

Personal resources modeled as Semantic Web
services


Service profile
Each user has a Semantic eWallet

Automated identification and access of a user’s
personal resources subject to privacy preferences
Copyright ©2001-2004 Norman Sadeh
Semantic Web Approach

Ontologies to explicitly represent and reason about:
 Personal/Contextual Resources
 Location tracking, calendar, organizational resources,
messaging resources, preferences, etc.
 Contextual attributes
 e.g. location, calendar activities, social or
organizational context, etc.
 Preferences, incl. privacy preferences:
 Access control preferences
 “Obfuscation” rules
 Web services
 Automated service identification and access
Copyright ©2001-2004 Norman Sadeh
Personal Resource Ontology:
An Example
Personal
Resource
IS-A
Location
Information
Resource
Activity
Information
Resource
List of Friends
INSTANCE
CMU Location
Tracking
Microsoft Outlook
Calendar
Sprint PCS
Location Tracking
Copyright ©2001-2004 Norman Sadeh
MyCampus Project



Motivation:
 Campus as “everyday life microcosm”
Objective:
 Enhance campus life through context-aware
services accessible over the WLAN
Methodology:
 Involve stakeholders in the design
 Students and other members of the community
 Evaluate and extrapolate to other environments
 Mobile Commerce, Mobile Enterprise, etc.
Copyright ©2001-2004 Norman Sadeh
Overall Architecture
Semantic
Web-enabled
Context Resources
Calendar
Contextual
Ontologies
User’s Personal
Environment
e-Wallet
Location
Tracking
Personal Resource
Directory
(incl. Privacy Pref.)
Personal
Preference
Ontologies
Personal
Resource
Ontologies
Service
Ontologies
Internet and
Intranet Semantic
Web-enabled
Services
Semantic Web
Service Directory
Wireless
LAN
Social Context
Preferences
Task-Specific
Agents
Copyright ©2001-2004 Norman Sadeh
Semantic eWallet




Context-independent knowledge
 Name, email address, context-independent preferences
Context-dependent knowledge
 “When driving, I don’t want to receive instant messages”
Service invocation rules
 Automated service identification and access
 Map contextual attributes onto different resources (personal
and public)
Privacy rules
 Access control rules
 “Only my classmates can see my location”
 Obfuscation rules
 “My classmates can only see the building I am in but
not the actual room”
Copyright ©2001-2004 Norman Sadeh
Location Tracking as Web Service
Location Tracking
as a Web Service
Copyright ©2001-2004 Norman Sadeh
Query context
Query
assertion
Asserting elementary needs for Pre-check
authorized information
access rights
eResult
Assertion of
authorized knowledge
Application of
obfuscation rules
Fetch useful
static knowledge
Call relevant
external services
Post-check
access rights
Example : Query from John inquiring about Mary’s location
 the sender of the query is John
 John’s query requires accessing Mary’s location
1.Is John allowed to see Mary’s location given what we know
about the context of the query?
2.Mary said she only allows colleagues to see her location when
she is on campus
3.John is a colleague of Mary
 Access location tracking functionality or Mary’s calendar
 Is Mary on campus?
 Mary is willing to disclose the building but not the room she is in
 Mary is in Smith Hall
Copyright ©2001-2004 Norman Sadeh
User Interaction
Agent
Agent Management
Agent (FIPA)
e-Wallet Manager
Agent
Ontologist
Agent
FIPA ACL messages and OWL Content
Directory Facilitator
Agent (FIPA)
Task-Specific
Agents
JADENorman
platform
Copyright ©2001-2004
Sadeh
HTTP Request
User Interaction
Agent
Agent Management
Agent (FIPA)
e-Wallet Manager
Agent
Ontologist
Agent
FIPA ACL messages and OWL Content
Directory Facilitator
Agent (FIPA)
Task-Specific
Agents
JADENorman
platform
Copyright ©2001-2004
Sadeh
Design of an e-Wallet



Three-layer architecture: security through
typing
 Core knowledge: User static & contextsensitive knowledge
 Service Layer: Automatic identification
and invocation of external sources
of knowledge (e.g. public web services
and and personal resources)
 Privacy layer: Enforces privacy rules
access control & obfuscation
All facts represented in OWL
Backward chaining migration rules: privacy
rules, service rules, static migration rules
privacy
service
Core
Knowledge
query
answer
Copyright ©2001-2004 Norman Sadeh
Design of an e-Wallet

Three-layer architecture: security through
typing
 Core knowledge: user static & contextsensitive knowledge
 Service Layer: automatic identification
and invocation of personal and public
semantic web services
 Privacy layer: enforces privacy rules
access control obfuscation rules
Query context
Query
assertion
Result
privacy
service
Core
Knowledge
query
answer
Asserting elementary needs for Pre-check
authorized information
access rights Fetch useful
static knowledge
Assertion of
authorized knowledge
e-
Application of
obfuscation rules
Call relevant
external services
Post-check
access
rights
Copyright
©2001-2004 Norman Sadeh
Implementation Details
OWL
Meta-model
in CLIPS
Ontology
in OWL
&
Ontology
stylesheet
Ontology
in CLIPS
Annotation
in OWL
&
Annotation
stylesheet
Annotation
in CLIPS
Rule
in (R)OWL
&
Rule
stylesheet
Rule
in CLIPS
Services
in (W)OWL
&
Service
stylesheet
Service rule
in CLIPS
Privacy
in (S)OWL
&
Privacy
stylesheet
Privacy rule
in CLIPS
Query
in (Q)OWL
&
Query
stylesheet
Query rules
in CLIPS
XSLT Engine
Result
in OWL
JESS
Copyright ©2001-2004 Norman Sadeh
Visualizing & Editing Preferences
Visualizing & editing a privacy rule
Copyright ©2001-2004 Norman Sadeh
Editing Based on Existing Ontologies
Copyright ©2001-2004 Norman Sadeh
Obfuscation Example

User location finder
City block level
City level level
Copyright ©2001-2004 Norman Sadeh
Slide Projector Agent
Copyright ©2001-2004 Norman Sadeh
Empirical Evaluation



Initial prototype working on Carnegie Mellon’s campus
 Restaurant concierge agent, message filtering agent,
etc.
 Integration with calendar, location tracking, user
profile, etc.
Evaluation
 Context awareness adds value
 Requires access to a broad range of resources/attributes
 Privacy concerns have to be addressed
Additional validation on context-aware enterprise and DoD
applications
Copyright ©2001-2004 Norman Sadeh
Concluding Remarks






Context awareness helps overcome the limitations of
mobile devices and the time criticality of mobile
scenarios
Context awareness makes privacy even more critical
Our experiments indicate that user preferences are
often complex
 Incl. context-sensitive preferences
Capturing these preferences is far from trivial
 Default profiles, learning, dialogs,
 How far can we go?
Semantic Web approach
 Allows for policies that refer to concepts
introduced in any number of domain-specific
ontologies
Opportunities for reconciliation with P3P/APPEL
Copyright ©2001-2004 Norman Sadeh
Q&A
Source:http://www.firstmonday.org/issues/issue
4_9/odlyzko/index.html
Copyright ©2001-2004 Norman Sadeh