We develop a new technique whereby a poll worker can determine whether the software executing on electronic voting machines on election day has been altered from its factory version. Our generalized approach allows a human, using a known challenge-response pair, to detect attacks that involve modification or replacement of software on a computer based on the time it takes the computer to provide a correct response to a challenge. We exploit the large difference between main memory access times and cache memory access or CPU clock cycle times to significantly increase the time required to compute the right response when the software has been changed.

The electronic voting machines known as Direct Recording Electronic (DRE), that are used in many states in the US have been shown to contain security vulnerabilities [16, 9, 3]. One of the problems is that the elections held on these machines cannot be independently audited. In this paper we address this issue by designing a new all-electronic independent audit framework for DRE voting systems. Our framework leverages system virtualization concepts and image recognition techniques to maintain an audit of the vote totals. The architecture we present is a step towards meeting the software independence requirements as defined by Rivest et al. [21, 2]. We have implemented a prototype using the Diebold Accuvote TS DRE voting software and the XEN hypervisor and demonstrate that our system can achieve a robust election audit with negligible overhead.