Abstract

We construct a universally verifiable, cryptographic vote casting protocol that enables each voter to determine with high certainty via a receipt that her choices (intended votes) have been accurately represented in the input to a public tally. However, since the receipt, in isolation, can represent a choice for any candidate with equal probability, it does not enable vote buying or coercion. The key to making this possible is that the totality of information that the voter uses to convince herself of encrypted ballot integrity includes temporal information that is only available at the time the ballot is cast. We assume that, as with conventional voting systems, the act of casting takes place in a private environment – i.e. the “poll booth.” Under this assumption then, the scheme, in conjunction with a universally verifiable tabulation protocol, provides an end-to-end verifiable, secret vote receipt based election protocol that is coercion free. Intrinsically, the protocol is unconditionally secure, although for the sake of usability, the commitment of data is likely to be implemented via a secure oneway hash. The security of such an implementation would then depend on the one-way property of the hash function employed. The scheme requires no more computation or data processing from the voter than is performed by a bank customer at a typical ATM. Thus, it is very practical.

Citations