The Byzantine Firing Squad Problem

Abstract

A new problem, the Byzanntine Firing Squad problem, is defined and solved in two versions, Permissive and Strict. Both problems provide for synchronization of initially unsychronized processors in a synchronous network, in the absense of a common clock and in the presence of a limited number of faulty processors. Solutions are given which take the same number of rounds as Byzantine Agreement but might transmit r times as many bits, where r is the number of rounds used. Additional solutions are provided which use at most one (Permissive) or two (Strict) additional rounds and send at most n^2 bits plus four times the number of bits sent by a chosen Byzantine Agreement algorithm.