"Even so, it's an unpleasant place to be in to have to use these machines that are so hackable," Appel said. "Early next week, I'm going to have to go out and cast my vote on one of these machines."
The problem, according to the report, is that there are many opportunities in the storage, distribution and deployment of the DRE machines where an unauthorized person could manipulate them and not be detected.
"Somebody could have hacked it at any time" during those stages before an election, Appel said.
Michelle Shafer, a spokeswoman for Sequoia Voting Systems, said in an e-mailed response that the company emphatically denies the conclusions of the Princeton report.
In a 19-page response posted on Sequoia's Web site, the company argues that the researchers who contributed to the report removed factory security hardware from the tested machine before they performed their analyses. The Sequoia response also says that an operator panel cover was not in place when the testing was conducted, which would have made a potential attack "far less likely to succeed before they are stopped, or at minimum, detected."
The Sequoia response also harshly criticizes the researchers as having an "inflammatory tone" about the company's DRE machines, while "editorializing on the wonders of paper ballots and optical scanning" as an alternative and more trusted method of voting. The company said the Princeton report includes "numerous factual errors and cases of intellectual dishonesty."
Appel defended the report's conclusions.
"There's no perfect technology [for e-voting], but I think the consensus of computer scientists is that precinct-counted, optically scanned paper ballots is the best method" in terms of reliability and accurate recount auditing, Appel said. "The voter fills out a paper ballot that is scanned and counted in their precinct. You have your numbers right at the close of the polls, with two independent records -- the computerized numbers and the pile of paper ballots in the sealed ballot box."