Simulating authenticated broadcasts to derive simple fault-tolerant algorithms

Fault-tolerant algorithms for distributed systems with arbitrary failures are simpler to develop and prove correct if messages can be authenticated. However, using digital signatures for message authentication usually incurs substantial overhead in communication and computation. To exploit the simplicity provided by authentication without this overhead, we present a broadcast primitive that provides properties of authenticated broadcasts. This gives a methodology for deriving non-authenticated algorithms. Starting with an authenticated algorithm, we replace signed communication with the broadcast primitive to obtain an equivalent non-authenticated algorithm. We have applied this approach to various problems and in each case obtained simpler and more efficient solutions than those previously known.