From partial consistency to global broadcast
M. Fitzi, Ueli M. Maurer · 2000
This paper considers unconditionally secure protocols for reliable broadcast among a set of n players, some of which may be corrupted by an active (Byzantine) adversary.In the standard model with a complete, synchronous network of pairwise authentic communication channels among the players, broadcast is achievable if and only if the number of corrupted players is less than n/3.We show that, by extending this model only by the existence of a broadcast channel among three players, global broadcast is achievable if and only if the number of corrupted players is less than n/2.Moreover, for this an even weaker primitive than broadcast among three players is sufficient.All protocols are efficient.