Touch-Screen Voting Machines Not Counted On
Security experts say optical scan best way to ensure election accuracy
February 13, 2008 —
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In Avi Rubin’s eyes, the best way to improve direct-recording electronic voting machines, or DREs, is to stop using them altogether.
Rubin, a computer science professor at Johns Hopkins University and longtime critic of electronic voting methods of all stripes, said that U.S. states are moving away from the questionable DRE machines, also known as touch-screens, to optical scanning, and he couldn’t be happier.
The issue has come to the fore again during this primary voting season in the United States, as Americans in both the Democratic and Republican parties choose their candidate for the November presidential elections.
Using optical scan machines, voters fill in an oval beside the name of a candidate, and the optical scan could reject an invalid ballot. Because it uses a paper ballot for scanning, this method offers the ability to audit ballots and perform recounts, while DREs keep vote totals on computer file and lack ballots.
“You just have to trust that everything is working correctly inside the machine,” Rubin said. “I think optical scan has its own challenges, but it does provide a mechanism to audit the election, which I don’t think should ever be compromised. The optical scanners are computers just like the touch-screens, but they have much less code in them, and less code means fewer bugs, and it’s easier to audit.”
Rubin knows all too well about the vulnerabilities of electronic machines. In 2004, he manually reviewed leaked source code from Diebold electronic voting equipment and discovered problems. Since then, he has been urging states to move away from DREs.
Questions Surround DREs
The most common vulnerability found in the machines’ software is memory buffer overflows, according to Rob Rachwald, product marketing director at Fortify Software, which sells testing software for security.’s director of product marketing. By using the overflow condition to bypass normal operation, hackers could potentially adjust the vote count or eliminate votes by bringing down a system.
Another issue uncovered by Fortify’s SCA scanner was vulnerabilities in password storage for the administrators who access the machines.