Key management in wireless sensor networks

Kevin Wang

About WSN

• What is wireless sensor networks?– Definition

• Inexpensive, limited resources…

– Constraints• Limited power, computing ability, memory size and

communication protocol

– Application • Military or hospital…

For example• Berkeley-designed MICA2

– 8 Mhz Atmel CPU – Instruction memory size is 128 kb – Data usage is 4 kb of RAM – Flash memory size is 512 kb – 19.2 kbps application bandwidth up to a range of 10–20

meter – At full power the MICA2 will run for about two weeks

before exhaustion and up to one year using sleep modes– Tiny OS

Security Risks in Wireless Sensory Networks

• Eavesdropping– Confidentiality

• Packet Injection– Access control– Integrity

• Jamming• Replay• Denial of Service

Adversary

K

K K

K

Problems

• Focus on– Key management– Clustering and Routing problem– Power consumption – Handoff problem

• Mobile node

Key management for WSN 1/4

• Models– Hierarchical and Distributed WSN

Key management for WSN 2/4

• Communication types– Unicast

• Nodes to headers

• Nodes to nodes

• Header to header

– Multicast • Header to nodes

– Broadcast• Server to nodes

• Server to headers

Key management for WSN 3/4

• Key predistribution types– Deterministic

– Probabilistic

– Hybrid

Key management for WSN 4/4

• Dynamic key generation algorithms for distributing– Pair-wise

– Group-wise

– Network-wise

Clustering problem

• Cluster problem– Random deployment

• Need an efficient algorithm to cluster

– Use deployment knowledge

• Impracticable or infeasible: DDHV-D scheme

Routing problem

• Routing problem– Shortest path is good?

– Find dynamic paths to reach max-life of WSN

– Solution:• Static

– GA, NN, …

• Mobile– Dynamic tiny GA…

Power consumption

• In WSN, the energy is an important dominated factor• Deliver messages will consumption much energy

– Deliver one bit : execute one instruction = 200~2900 : 1

• But if fix the key function then the entire WSN will be weakness.

• So we consider power constraint and propose a novel scheme– Dynamic key-generation function– And the key function fulfill the power constraint

Handoff problem

• No move no handoff • Mobile nodes

– Headers verse nodes

– In mobile WSN, as nodes moving, then the secure problem will be more important. ?

Question

Our scheme