Definitions and Security of Quantum Electronic Voting

Abstract

Recent advances indicate that quantum computers will soon be reality. Motivated by this ever more realistic threat for existing classical cryptographic protocols, researchers have developed several schemes to resist “quantum attacks.” In particular, for electronic voting (e-voting), several schemes relying on properties of quantum mechanics have been proposed. However, each of these proposals comes with a different and often not well-articulated corruption model, has different objectives, and is accompanied by security claims that are never formalized and are at best justified only against specific attacks. To address this, we propose the first formal security definitions for quantum e-voting protocols. With these at hand, we systematize and evaluate the security of previously proposed quantum e-voting protocols; we examine the claims of these works concerning privacy, correctness, and verifiability, and if they are correctly attributed to the proposed protocols. In all non-trivial cases, we identify specific quantum attacks that violate these properties. We argue that the cause of these failures lies in the absence of formal security models and references to the existing cryptographic literature.

A Two-Party Quantum Parliament

“…[15] proposed a new quantum election protocol that, besides fulfilling the typical requirements, also satisfies the receipt-freeness property. An interesting critique regarding quantum voting protocols is found in [16], highlighting the lack of rigor in terms of definitions and proofs used to ascertain their security and efficiency.…”

Efficient Quantum Voting with Information-Theoretic Security

“…Even if the encrypted information is stored, no future advances in computational power will enable its decoding. This observation has spurred active development of quantum voting protocols, see, e.g., [10] for a recent review. However, existing approaches are either inefficient or do not satisfy all desirable security criteria.…”

“…explored the use of distributed entangled states to compute the voting function, their security is not rigorously established, especially in practical settings. For instance, quantum communication that is exponential in the number of voters is required to prevent doublevoting [10,13].…”

“…We provide definitions for the security properties of a voting protocol, accounting for information-theoretic security. Compared to prior work [10] in the setting of computationally-bounded adversaries, our properties account for the more general setting of informationtheoretic security and therefore provide a stronger security guarantee. We then prove that our protocol satisfies these properties.…”

Quantum and Classical Bayesian Agents

“…Quantum versions of Merlin-Arthur protocols [6,7] require transmission of quantum information between differently capable agents: Merlin, a wizard, can magically produce quantum proofs and send them to Arthur, a human, who might hope to verify the proofs with the aid of a quantum computer. Another potential multi-agent scenario is information theoretically secure quantum voting [8,9]. When multiple agents are involved, phenomena related to their coordination, cooperation, and even competition may become nontrivial.…”