Remote authentication over a long range wireless network using large signature keys such as biometric samples (fingerprint, retinal scans etc.) is soon going to become an integral feature of various kinds of transactions. In the domain of mobile and ad hoc networking, this will become even more relevant due to the intrinsic dynamism in the applications. Because of the large size of the authentication keys, and continual need for authentication, considerable power and bandwidth are consumed by such a process. Authentication being only a background process supporting other transactions, should not take away too much of resources, especially bandwidth and power that are quite critical for small mobile devices.

We present LAWN, a light-weight authentication protocol for wireless networks that trades computation for communication and can be tuned for any desired security guarantee. For an authentication token of length n, LAWN prepares a small sketch of length O(log n) (adding very low computational overhead), and transmits the sketch over the network. Under a reasonable energy consumption model, we show that this technique results in 70% to 80% saving in power for long-range wireless applications.