Lightweight key agreement with key chaining

Small ad-hoc wireless networks are becoming ubiquitous. Wireless protocols like ZigBee, ANT, and Bluetooth have been targeted towards small devices with limited capabilities. As the volume and sensitivity of data being communicated over these networks increases so does the need for security. The limited capabilities of these devices, however, means the standard in security is out of their reach. Cost and power factors prevent devices from being able to run public key (PK) cryptographic algorithms and standard block ciphers. Using the Needham-Schroeder (NS) symmetric key protocol, we show how Hummingbird, an ultra lightweight symmetric key algorithm, can be used to establish trust between a node and an authentication server (AS). The AS can then use the trust it shares with all nodes in the network to facilitate secure communication between two nodes previously unknown to each other. It also over comes the NS vulnerabilities and provides backwards secrecy up to the point a node is compromised.