John Bethencourt Dan Boneh Brent Waters Cryptographic Methods for Storing Ballots on a Voting Machine. 2007 NDSS http://www.isoc.org/isoc/conferences/ndss/07/papers/cryptographic_methods_for_storing_ballots.pdf conf/ndss/2007 db/conf/ndss/ndss2007.html#BethencourtBW07