Computational Policies in a Need to Share Environment

1
Computational Policies in a Need to Share
Environment

• Tim Finin
• University of Maryland,Baltimore County

2
Introduction

• Comments on the role of and require-ments for
  computational policies in todays environment
• Web, 9/11, pervasive computing,
• Ideas in development in collaboration with
  colleagues from UT Dallas, GMU, and MIT

3
Background

• Weve been working on computational policies
  since about 1999
• Started with XML encoded horn clauses for supply
  chain mgmt pervasive computing
• Moved policy research to the Semantic Web in
  2002
• Lalana Kagal developed Rei in her dissertation
• Applications have varied
• Also enhanced P3P, service matching and
  selection, collaborative teams, RDF store access,
  and distributed router configuration.

4
Policy-based Automated Wide-Area Network
Configuration and Management
Goal self configuring network routers running
in a coalition envi-ronment demonstrating
constraints on border gateway protocol
5
General approach

• A computational policy describes a systems
  actions or behavior
• Describes can be
• Specifies whenever X, do Y
• Constrains doing X is permitted
• Advises whenever X, doing Y is preferred to
  doing Z
• Public policies and common policies foster
  interoperability and cooperation

6
Some lessons learned

• Most of the work in developing a policy is in
  developing the domain ontology
• Often the constraints are simple, e.g., For
  faculty use only
• Sharing policies means sharing domain models
• The Semantic Web offers a sound and practical
  approach for shared domain models

7
Some lessons learned

• Several approaches to encoded the rules or
  constraints part of policies
• Descriptions of permitted, forbidden and obliged
  classes of actions (KAOS)
• Using rule extensions to RDF (Rei, Rein)
• Some approaches are problematic
• E.g., uncertainty, probabilities, defaults
• But OWL can do the heavy lifting in reasoning
  about the terms
• Is Mary a full-time faculty member from a
  higher-educational institution? Whats the
  evidence?

8
New Requirements

• 9/11 and related events illustrated problems in
  how sensitive information is managed
• Managing information and services on the Web with
  appropriate security and privacy and simplicity
  is increasingly important and challenging
• Autonomous devices like mobile phones, routers
  and medical equipment need access too.

9
Need to Know, Need to Share

• Traditional information security frame-works are
  based on need to know
• Unless you can prove that you have a pre-arranged
  right to this information, you cant have it
• The 9/11 commission recommended moving from this
  to need to share
• I think this information may be important for you
  to accomplish your mission and would like to
  share it with you

10
Need to Know, Need to Share

• Traditional information security frame-works are
  based on need to know
• Unless you can prove that you have a pre-arranged
  right to access this information, you cant have
  it
• The 9/11 commission recommended moving from this
  to need to share
• I think this information may be important for you
  to accomplish your mission and would like to
  share it with you

11
Just a slogan?

• For need to share to be more than just a
  political slogan, we need to under-stand what it
  might mean technically
• and to explore its feasibility and desirability
• and the risks and benefits

12
Required Capabilities

• Semantic Interoperability
• Unknown principals
• Context
• Speech acts and negotiation
• Adjustable privacy
• Usage control, enforcement, accountability
• Explanations and provenance
• Ramifications

13
Semantic Interoperability

• Having a shared policy requires that the parties
  agree on
• The semantics of the policy language (e.g., is
  everything not explicitly forbidden allowed?)
• The semantics of the domain ontology (e.g., whos
  a faculty member?)
• The Semantic Web is a big win here.

14
Unknown Principles

• Standard access control is based on
  authentication
• I have a list of who can do what. Just prove to
  me which of these people you are
• In open environments (Web, pervasive computing)
  this wont work
• We can control access based on their their
  (provable) attributes
• Prove youre a current UMBC student to use the
  printer

15
Context

• Whats forbidden in a normal situation may be
  allowed in a life-threatening emergency
• Context descriptions (e.g., tags) can identify
  the current situation
• Policy rules can be conditioned by context
• E.g., as guards on rules or by enabling/
  disabling policy modules

16
Adjustable privacy

• One way to enforce privacy is to not divulge
  information
• Another is to provide general answers
• Wheres John?
• 47.670412403362256, -122.12013959884644
• In Redmond
• In Washington state
• On travel
• Policies can control the granularity of answers
  given to different queries

17
Usage control and accountability

• Enforcing policies can be a difficult issue in
  open, distributed systems
• MITs policy aware approach is exploring
  accountability for use
• Policy violations can be detected in logs
• Theres lots more to usage constraints
• E.g., DRM policies constrain how often you can
  perform certain operations on an object
• Systems need to reason about there own behavior
  as well as that of others

18
Explanations and provenance

• Explaining why a policy decision holds or doesnt
  hold can be important
• Explaining why a constraint does not hold
  continues to be a difficult task
• The explanation may involve provenance, citing
  the source for the facts and policy constraints
  used

19
Utility and Ramifications

• In some environments, the utility of data may be
  a factor in whether to share or not
• This requires reasoning about the requestors
  tasks, the datas relevance to them and the
  availability of alternate data
• This may also require Bayesian reasoning
• Whats the likelihood that the patient might have
  diabetes?
• In general, a system might reason about the risks
  and benefits of sharing vs.. not sharing the data

20
Planned Architecture
21
Conclusion

• Managing information in open, distributed
  environments with appropriate security and
  privacy is increasingly important
• Computational policies can help
• Semantic Web technologies offer a way to share
  common policy concepts, policies, and domain
  models
• Other representation and reasoning compo-nents
  will be needed for many application domains.

22
http//ebiquity.umbc.edu/