a key management scheme for distributed sensor networks
DESCRIPTION
A Key Management Scheme for Distributed Sensor Networks. Laurent Eschaenauer and Virgil D. Gligor. Introduction. Constraints Problems with Current Solutions Key Distribution Key Revocation, Re-Keying, and Node Capture Resiliency Analysis and Simulation Problems. Constraints. Power - PowerPoint PPT PresentationTRANSCRIPT
A Key Management Scheme for Distributed Sensor Networks
Laurent Eschaenauer and
Virgil D. Gligor
Introduction
Constraints Problems with Current Solutions Key Distribution Key Revocation, Re-Keying, and
Node Capture Resiliency Analysis and Simulation Problems
Constraints
Power Computation Key Transmission Digital Signatures
Storage Space Code Keys
Problems with Current Solutions
Global Keys Compromise Is Drastic
Pair-Wise Keys Storage Problems Inefficiency Re-keying and Node Additions Are
Expensive
Key Distribution Key pre-distribution phase
Preconfigured keys Generation of key pool Randomly chosen sets of keys from key
pool key ring Probability 2 nodes share key is very
high Key identifiers are remembered by
base station, and base station shares key with every node
Key Distribution Cont’d.
Shared key discovery phase Nodes broadcast key identifiers If 2 nodes share a key identifier then
a secure link is set up Links at routing layer are only set up
if a shared key exists Can protect this exchange with a
encrypted challenge
Key Distribution Cont’d.
Path key establishment phase Enables two nodes not sharing a key
to communicate via a multi-hop link Relies on the fact that many keys on
a key ring remain unused after shared key discovery phase
Revocation Revoke keys of a compromised node Base station broadcast a signed
message containing all keys to be removed from key ring
To sign message base station generates new key and unicasts it to each node
Node uses this key to verify signature of revocation message
Re-Keying
Keys may have a lifetime shorter than that of node
Nodes simply remove key from key ring and begin shared key discovery phase again
Node Capture Resiliency
2 threat levels Sensor input manipulation Bogus data Difficult to detect, harder to prevent Data correlation for redundant
sensors Physical Compromise
Tamper-proof construction
Node Capture Resiliency Cont’d.
Automatic key erasure Global key = complete compromise Pair-wise keys = n-1 links to
compromised are available Key distribution scheme = k << n are
compromised
Analysis Probability and Graph Theory
Expected degree of a node to ensure connectivity?
Sizes of key ring, key pool, and network
Analysis Cont’d. Key sharing
probabilities Logarithmic
increase: as network size increases key ring increases logarithmicaly
Simulations Effects on Network Topology
Dependent on size of key ring Multi-hop neighbors can use path only once
Simulations Cont’d.
Simulations Cont’d. Resiliency revisited
Node compromise limits number of links attacker gains access to:
Analysis
Relatively simple operation Complicated staging and pre-
deployment Need to take future into account
when deciding on key-sizes and key-lifetimes.
Achieves relatively low power and computation
Problems No authentication in key discovery phase Open to selective forwarding attack:
Compromised node C tells hears node A tell node B it has key 4. C then tells A it also has key 4. A might then send info to C, and C can drop packets.
Limited since C can’t actually encrypt anything since it doesn’t actually have key 4.
Problems Cont’d.
Compromised node could keep broadcasting a different key identifier list causing neighbors to waste bandwith searching their key list.
Sibyl attack where compromised node repeatedly sends out different key identifier lists. Possibly making a nodes link table grow too large