Short Ballot Assumption and Threeballot Voting Protocol* Jacek Cichon, Miroslaw Kutylowski, Bogdan Weglorz We analyze Threeballot voting system proposed recently by R. Rivest. We analyze the size of the list of the candidates that enables immunity to Strauss' attack. We also show that in a reasonable scenario it is impossible to reconstruct voters' preferences for a single two options voting. * Current Trends in Theory and Practice of Computer Science (SOFSEM) 2008 To appear in LNCS, Springer-Verlag