Trust Context Spaces an Architecture for Security in Pervasive Computing SPC 2003, Boppard Germany, 13.03.2003

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Trust Context Spacesan Architecture for Security
in Pervasive ComputingSPC 2003, Boppard
Germany, 13.03.2003

• Philip Robinson Michael Beigl
• Telecooperation Office
• University of Karlsruhe

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Key Terms just to put things in context

• Context
• Interactive Context
• Security Context
• Trust Context

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Context

• any information that can be used to
  characterize the situation of an entity, where an
  entity can be a person, place, or physical or
  computational object. (Abowd, Dey, 1999)

Physical Context
Application (Computational) Context
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Interactive Context

• any information that characterizes the state of
  an interaction (more than one entity), including
  the identites involved, relationships formed
  (sessions established), accessible data and
  operations.

Physical
Physical
Application (Computational)
Application (Computational)
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Security Context

• any information that characterizes the policies
  and mechanisms used to meet the protection
  requirements, and hence safeguard the current
  interactive context

Physical
Physical
Application (Computational)
Application (Computational)
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Trust Context

• any information that can be used to characterize
  the evidence and assurances that the security
  context for a particular interactive context is
  and will be maintained.

Physical
Physical
Application (Computational)
Application (Computational)
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What has changed in Pervasive Computing?

• Greater overlap of physical and virtual
  environments
• Networked Sensor technology led to Augmented
  Reality
• Physical actions and changes in the environment
  have more significance in computer applications
  (Context-Awareness)
• Virtual events have more real-world significance,
  without obtrusion (Ambient Technologies)
• The interactive context has been widened

Application (Computational) Context
Physical Context
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What has changed in Pervasive Computing?
Each sector represents the scope of identities,
sessions, accessibility of data and operations
The implicitly shared interactive context has
been widened
Personal Interactive Context
Implictly Shared Interactive Context
Explictly Shared Interactive Context
Public Interactive Context
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but may result in...
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Security Vulnerability Windows
physical
virtual
Value of Context Information
Time (t)
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Goals of Trust Context Spaces

• Minimize occurences of Security Vulnerability
  Windows
• Control the security risks associated with
  implicitly shared information

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Principle 1Equilibrium of Physical and Virtual
Security

• Perception physical cues for security translated
  into invocation of virtual security mechanisms
• Actuation virtual security-related events
  produce active notification or adaptation of
  physical environment

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Principle 2Trust in the Environment

• Some trust decisions are offloaded to the
  environments security services (natural
  behavior)
• Environment rooms, offices, buildings etc. A
  definite space
• A Trust Context Space therefore has both physical
  and virtual properties implying both physical
  and virtual identities, assets, operations, and
  relationships

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Principle 3Shared Unique Context as a Basis for
Security

• A good secret key must not be repeatable or
  easily derived
• Efforts to facilitate yet secure implicit
  interaction
• The more parties interact, the more unique their
  shared context becomes (cumulative trust)

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Architecture
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Scenario
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Conclusion Contributions Evaluation

• Incubation of virtual identities/ counterparts
  within Controlled spaces (meeting rooms,
  offices...)
• Public Trust Context Spaces are further challenge
• Entropy of context information has to be taken
  into consideration, if being used for implicit
  key generation