Efficient batch authentication for hierarchical wireless sensor networks

Authentication in wireless sensor networks is critical, as they are often deployed unattended in hostile environments and must transmit information over unsecured mediums. However, the cost of performing cryptographic operations is an extremely limiting factor because sensor devices and related equipment are constrained by storage and computational ability. The problem is further compounded by the fact that one device (typically a base station) may be required to perform a large number of verifications proportional to the number of sensing devices. This paper investigates the efficiency of message authentication in hierarchical wireless sensor network systems. Scenarios are explored for verifying messages as a batch process, thereby saving overhead and computation. If a device is incapable of performing verification, it can sign the batch and pass it up the hierarchy to another device to undertake the verification procedure. This effectively overcomes many problems with power, storage and computational constraints. We contrast two approaches based on message authentication codes and short digital signatures. A framework is presented for how digital signatures can be used for batch authentication within a hierarchical wireless sensor network.