Interconnecting lock-step synchronous fault-tolerant systems based on voting and error-correcting codes

Abstract

The correctness of the behavior of a fault-tolerant system depends among other things on the correct distribution of the data descending from unreliable I/O devices over the modules of the fault-tolerant system, the so-called input-problem. More generally, a maliciously behaving system, whether it is fault-tolerant or not, should never defeat a correctly functioning fault-tolerant system, i.e. a system which does not contain more faulty modules than it is designed to tolerate. This paper presents a new class of synchronous deterministic non-authenticated algorithms for reaching Byzantine agreement on data descending from other (fault-tolerant) devices. The algorithms are based on voting and error-correcting codes and require considerably less data communication than the existing algorithms, whereas the number of rounds and the number of modules meet the minimum bounds.