Cryptographic Voting Protocols Research Articles

Implementing Broadcast Channels with Memory for Electronic Voting Systems

To provide universal verifiability, cryptographic voting protocols often require a broadcast channel to spread the election data to the public. The basic requirements on such a broadcast channel are similar for most protocols, for example that the channel maintains a memory of all broadcast messages and that nothing can be deleted from the channel’s memory. In this paper, we provide a formal definition for such broadcast channels with memory and describe their properties. We also analyze the significance of a broadcast channel with memory in cryptographic voting protocols and propose that such a channel is provided in form of a service that we call bulletin board. Based on this service, we analyze some real-world problems that cryptographic voting protocols might have and provide possible solutions. For this we define a generic interface for the main board functionalities, which offers a flexible way of extending the basic properties of a bulletin board to comply with all sorts of additional requirements.

Receipt-free remote electronic elections with everlasting privacy

We present a new cryptographic voting protocol for remote electronic voting that offers three of the most challenging features of such protocols: verifiability, everlasting privacy, and receipt-freeness. Trusted authorities and computational assumptions are only needed during vote casting and tallying to prevent the creation of invalid ballots and to achieve receipt-freeness and fairness, but not to guarantee vote privacy. The implementation of everlasting privacy is based on perfectly hiding commitments and non-interactive zero-knowledge proofs, whereas receipt-freeness is realized with mix networks and homomorphic tallying.

Shuffle-Sum: Coercion-Resistant Verifiable Tallying for STV Voting

There are many advantages to voting schemes in which voters rank all candidates in order, rather than just choosing their favorite. However, these schemes inherently suffer from a coercion problem when there are many candidates, because a coercer can demand a certain permutation from a voter and then check whether that permutation appears during tallying. Recently developed cryptographic voting protocols allow anyone to audit an election (universal verifiability), but existing systems are either not applicable to ranked voting at all, or reveal enough information about the ballots to make voter coercion possible. We solve this problem for the popular single transferable vote (STV) ranked voting system, by constructing an algorithm for the verifiable tallying of encrypted votes. Our construction improves upon existing work because it extends to multiple-seat STV and reveals less information than other schemes. The protocol is based on verifiable shuffling of homomorphic encryptions, a well-studied primitive in the voting arena. Our protocol is efficient enough to be practical, even for a large election.

Stop the Presses: How Paper Trails Fail to Secure E-Voting

Americans trust computers to run critical applications in fields such as banking, medicine, and aviation, but a growing technophobic movement believes that no computer can be trusted for electronic voting. Members of this movement claim that in order to have secure elections, Americans must revert to paper ballots. Such claims are not only incorrect but attack the very foundation of our digital society, which is based on the knowledge that information can be reasonably secured. Clearly, no system with a human element - including electronic and nonelectronic voting machines - is error-proof, and specific versions of certain voting machines have security weaknesses. Neither of these facts, however, should be taken as a universal indictment of e-voting. Direct recording electronic (DRE) voting machines are electronic machines, similar to ATMs, that let voters view ballots on a screen and make choices using an input device such as buttons or a touchscreen. Some opponents of electronic voting are lobbying for legislation that would require so-called voter-verified paper audit trails for all DRE voting machines. The purpose of the paper audit trails would be to provide proof that the DRE voting machines functioned correctly. Unfortunately, as discussed in this report, paper audit trails for DRE voting machines have several shortcomings. They do not provide complete security to voters and they increase costs and risks. Furthermore, requiring voter-verified paper audit trails would prevent the use of innovative voting technology that offers voters more security, transparency, and reliability than can be delivered with paper audit trails alone. Congress is now considering legislation that would mandate that all DRE voting machines have voter-verified paper audit trails, and many states will vote on similar legislation this year. We believe it is time for the debate on e-voting technology to move beyond a discussion of paper audit trails. To restore voter confidence and promote secure election technology in the United States by ensuring that states can continue to improve their voting systems, this report recommends the following: * Congress and the states should allow the use of fully electronic ballots, not restrict electronic voting systems to those that create paper ballots. * Congress and the states should require that future voting machines have verifiable audit trails, not require machines that create verifiable paper audit trails. * Congress should provide funding for the U.S. Election Assistance Commission to issue grants for developing secure cryptographic voting protocols and for pilot testing of new voting technology.