A distributed, end-to-end verifiable, internet voting system

E-voting systems have emerged as a powerful technology for improving democracy by reducing election cost, increasing voter participation, and even allowing voters to directly verify the entire election procedure. Prior internet voting systems have single points of failure which may result in the compromise of voter secrecy, service availability, or integrity of the election results. In this paper, we present the design, implementation, security analysis, and evaluation of a complete e-voting system that is distributed, privacy-preserving and end-to-end verifiable. An essential component of end-to-end verifiable e-voting systems, is a Bulletin Board (BB), i.e., a publicly accessible repository of information assisting in collecting votes, tabulating the result, and election auditing. In previous works, either the BB is a single point of failure and needs to be trusted, or in case it is distributed, its proper operation during ballot casting can only be verified by using a trusted device that performs cryptographic operations. Our system is the first e-voting system with a distributed BB whose operation is human verifiable, i.e., voters can verify its proper operation without the assistance of special software or trusted devices. A voter can use our system over the web, even when her web client stack is potentially unsafe, without sacrificing her privacy, and still be assured her vote was cast as intended. A voter can even outsource election auditing to third parties, still without sacrificing privacy. Finally, as the number of auditors increases, the probability of election fraud going undetected is diminished exponentially. We provide a rigorous security analysis, proving the safety and liveness properties of the system. We implement a prototype of the complete system, we measure its performance empirically, and demonstrate its ability to handle large-scale elections.