Post on 06-Jan-2016
description
Philip Robinson, TecO, Universität Karlsruhe
Trust Context Spacesan Architecture for Security in Pervasive Computing
SPC 2003, Boppard Germany, 13.03.2003
Philip Robinson & Michael BeiglTelecooperation OfficeUniversity of Karlsruhe
Philip Robinson, TecO, Universität Karlsruhe
Key Terms “just to put things in context”
• Context• Interactive Context • Security Context • Trust Context
Philip Robinson, TecO, Universität Karlsruhe
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)
PhysicalContext
Application(Computational)
Context
Philip Robinson, TecO, Universität Karlsruhe
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
Application(Computational)
Physical
Application(Computational)
Philip Robinson, TecO, Universität Karlsruhe
Security Context
• any information that characterizes the policies and mechanisms used to meet the protection requirements, and hence safeguard the current interactive context
Physical
Application(Computational)
Physical
Application(Computational)
Philip Robinson, TecO, Universität Karlsruhe
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
Application(Computational)
Physical
Application(Computational)
Philip Robinson, TecO, Universität Karlsruhe
What has changed in Pervasive Computing?
PhysicalContext
Application(Computational)Context
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
Philip Robinson, TecO, Universität Karlsruhe
What has changed in Pervasive Computing?
PersonalInteractiveContext
Public Interactive Context
Explictly Shared Interactive Context
Implictly Shared Interactive Context
Each sector represents the scope of identities, sessions,
accessibility of data and operations
The implicitly shared interactive context has been widened
Philip Robinson, TecO, Universität Karlsruhe
but may result in...
A
C
B
non-invitee enters
discussion stops, files areclosed
presenter stops
...but display is still active!!!
E
D ...printer is still printing!!!
...personal device is still broadcasting!!
Philip Robinson, TecO, Universität Karlsruhe
Security Vulnerability Windows
Time (t)
Value of Context
Information
discovery
trust decision
session(secure channel)
interaction
termination
W1
W2
physical
virtual
Philip Robinson, TecO, Universität Karlsruhe
Goals of Trust Context Spaces
Minimize occurences of Security Vulnerability Windows
Control the security risks associated with implicitly
shared information
Philip Robinson, TecO, Universität Karlsruhe
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
close / open
authenticate
encrypt / decrypt
briefcase
filingcabinet
businesscards date book
notes
Philip Robinson, TecO, Universität Karlsruhe
Principle 2:Trust in the Environment
• Some trust decisions are offloaded to the environment‘s 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
Philip Robinson, TecO, Universität Karlsruhe
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)
Philip Robinson, TecO, Universität Karlsruhe
Architecture
Environment
Smart Item/ HumanSmart Item/ Human
trustservices
policymanagement
contextmanagment
trustservices
policymanagement
contextmanagment
trustservices
policymanagement
contextmanagment
entitymapping
1
3
2
3
4
44
5
55
66
77
7
Philip Robinson, TecO, Universität Karlsruhe
Scenario
{personal space}
(A) Personal Trust Context Space
PersonalInformationDisplayed
Desk
PDA
Shelves
Door
Intercom
Environmental Services
wirelesscomm
Bridge
{implicit sharing}
{time}(B) IImplicit Shared Context Space
"Notification":Beep, Audio signal of
change in trust context
"Implicit Cue":Detect another
principalproximity,changinginteractive
trust context
"Explicit Cue":Switch PDA
off!
"ScreenSaver"
"Actuation":Relevant files
are closed
{shared space}
(C) Explicit Shared Context Space
SharedInformationDisplayed
Philip Robinson, TecO, Universität Karlsruhe
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