Scantegrity: End-to-End Voter-Verifiable Optical- Scan Voting

Randomized Partial Checking Revisited

“…Thus, we think it is fair to consider the issues we have identified as flaws in the protocol and not as mere implementation bugs, although we realize that different interpretations are possible. Both the Civitas [4] and the Scantegrity [3] teams have reported that they have already mended, or are about to mend, their implementations.…”

“…More precisely, we have discovered fully practical attacks on both the privacy and the correctness of their protocol and notable real world implementations of it, e.g., the Civitas voting system [4]. Using similar ideas we can also attack the correctness of related schemes, e.g., the Scantegrity voting system [3] that was used in real elections including Takoma Park City Municipal Elections 2009 and 2011. The most serious attack allows an adversary to replace the complete output of the mix-net without detection by corrupting a single mix-server, but we can also break the anonymity of targeted senders at low cost in terms of the number of corrupted senders.…”

“…A prominent research group in electronic voting generously gave us access to their private source code of their homomorphic mix-net with RPC and it suffered from this flaw. Another notable and publicly available example of an implementation with this flaw is the Civitas [4] election system (version 0.7.1), implemented by Clarkson et al The Scantegrity scheme [3] employs a checking approach that resembles random partial checking and suffers from this flaw.…”

Paperless Independently-Verifiable Voting

“…The protocols we describe and study in this paper were first informally proposed by Chaum, Popoveniuc and Vora [9]. We present slightly modified versions in this paper.…”

“…In this section we present a slight generalization of the protocol named eTegrity in [9]-a challenge-response-style protocol which is the natural extension of Helios to the AAHIP model. The voter familiar with the ballot audits of Prêt à Voter [16] or Scantegrity [6] will notice the similarity with ballot audits.…”