Paper 2008/193

A Tamper-Evident Voting Machine Resistant to Covert Channels

Wei Han, Tao Hao, Dong Zheng, Ke-fei Chen, and Xiaofeng Chen

Abstract

To provide a high level of security guarantee cryptography is introduced into the design of the voting machine. The voting machine based on cryptography is vulnerable to attacks through covert channels. An adversary may inject malicious codes into the voting machine and make it leak vote information unnoticeably by exploiting the randomness used in encryptions and zero-knowledge proofs. In this paper a voting machine resistant to covert channels is designed. It has the following properties: Firstly, it is tamper-evident. The randomness used by the voting machine is generated by the election authority. The inconsistent use of the randomness can be detected by the voter from examining a destroyable verification code. Even if malicious codes are run in the voting machine attacks through subliminal channels are thwarted. Next, it is voter-verifiable. The voter has the ability to verify if the ballot cast by the machine is consistent with her intent without doing complicated cryptographic computation. Finally, the voting system is receipt-free. Vote-buying and coercion are prevented.