Security in Sensor Networks By: Tracy Barger, David Friedman, and Stavan Parikh

Swarms ?? Group Behavior Bees ! MEMS (Smart Dust) MEMS – Microelctromechanical Systems Applications –Surveillance –Smart House –Grocery Shopping –FedEx tracking on Steroids

Environment Constraints Power Processor: 8 bit Memory: 15K RAM: 512 bytes Devices not individually addressable

Trust Model Base Station –Complete Trust –Requires Authentication Motes –Trust Self Broadcast Communication: Insecure –Need Encryption

Key Distribution and Encryption Use symmetric cipher Keys pre-initialized in motes Use J-secure scheme (NAI Paper) n nodes, y groups All nodes in a group have same key Note: If security is a priority, keys can be refreshed using a group key distribution scheme such as key graphs K1K1 K2K2

Group Size Tradeoffs What’s optimal group size? s = group size Tradeoff: security v. # communications v. memory Small, one-hop -- Use s = 1 1n s

Hash-based Authentication Generates X n ; Calculates key Chain: H(X n ) = X n-1 … H(X 1 )= X 0 M = E(Command || X i ) Mote decrypts M, Checks H(X i ) = X i-1 Then stores X i in place of X i-1

Conclusion Examined current security techniques –Key Distribution –Authentication Tradeoff between modifying existing and starting from scratch May be more beneficial to create new protocols Security will be defined by application