Privacy and Security in Embedded Sensor Networks

Daniel Turner

11/18/08

CSE237a

The Problem

Capture Attacks Wireless Communication Limited Power

Resource drain attack Extra message length costly

Limited Resources CPU: No asymmetric crypto RAM / Flash: minimal state

Confidentiality (Encryption)

Block Cipher: DES, Skipjack, AES, ... Init Vector:

Additional Randomness TinySec: CBC (10% pwr increase)

IV = 4 Bytes MiniSec: OCB (8.3% pwr increase)

No text expansion

Authenticity (MAC)

MAC: cryptographic secure checksum TinySec:

Replace CRC with MAC (3% pwr increase) MiniSec:

Instead of an IV OCB produces a MAC

Additional Areas

Secure Routing Prevent Black holes

Replay Attacks Counters and Bloom filters

Keying Global key Pair wise keys Something between

Future Work

Better Keying Methods Optimized Ciphers Break implicit assumptions about loose

synch between nodes

Questions?

Key Management

Bad: All pairs or Single key LEAP Keys

Base-station Pair: Computed at boot from K_in Cluster: pairwise sending of cluster key Global

re-keying: Controller revokes node, sends new key

Replay Attacks

TinySec: No protection MiniSec:

Counters in unicast (3 bit overhead) Bloom filter in broadcast

Secure Routing

Create a routing table using signed IDs Challenges: prevent liars No node duplication: prevent Sybil

Secure Routing

Secure Routing

Create a routing table using signed IDs Challenges: prevent liars No node duplication: prevent Sybil

Route via Multi-path forwarding 3 paths per group (Random) direction string

Honeybee to eliminate bad nodes