In secret ballot protocols, the unique voting property is crucial sinc
e without it a voter may vote more than once or his ballot may collide
with others and be discarded by the authority. In this paper we prese
nt a collision-free secret ballot protocol based on the uniquely blind
signature technique. Our proposed scheme can be used to hold large-sc
ale general elections because it ensures independence among voters wit
hout the need for any global computation. This scheme preserves the pr
ivacy of a voter against the authority and other voters. Robustness is
ensured in that no subset of voters can corrupt or disrupt the electi
on. The verifiability of this protocol ensures that the authority cann
ot present a false rally without being caught. Copyright (C) 1996 Else
vier Science Ltd