Paper 2022/543 Original: eprint.iacr.org/2022/543 ↗

Aura: private voting with reduced trust on tallying authorities

Abstract

Electronic voting has long been an area of active and challenging research. Security properties relevant to physical voting in elections with a variety of threat models and priorities are often difficult to reproduce in cryptographic systems and protocols. Existing work in this space often focuses on the privacy of ballot contents, assurances to voters that their votes are tabulated, and verification that election results are correct; however, privacy of voter identity is often offloaded to trust requirements on election organizers or tallying authorities, or implies other kinds of trust related to cryptographic construction instantiation. Here we introduce Aura, an election protocol that reduces trust on tallying authorities and organizers while ensuring voter privacy. Ballots in Aura are dissociated from voter identity cryptographically, use verifiable encryption and threshold decryption to diffuse trust in tallying authorities, require no trusted setup for cryptographic primitives, and use efficient proving systems to reduce computation and communication complexity. These properties make Aura a competitive candidate for use in a variety of applications where trust minimization is desirable or necessary.