Bruce Schneier writes in Forbes about electronic voting:
Electronic voting is like an iceberg; the real threats are below the waterline where you can’t see them. The problem is software — programs that are hidden from view and cannot be verified by a team of Republican and Democrat election judges, programs that can drastically change the final tallies. And because all that’s left at the end of the day are those electronic tallies, there’s no way to verify the results or to perform a recount. Recounts are important.
This isn’t theoretical. In the U.S., there have been hundreds of documented cases of electronic voting machines distorting the vote to the detriment of candidates from both political parties: machines losing votes, machines swapping the votes for candidates, machines registering more votes for a candidate than there were voters, machines not registering votes at all. I would like to believe these are all mistakes and not deliberate fraud, but the truth is that we can’t tell the difference. And these are just the problems we’ve caught; it’s almost certain that many more problems have escaped detection because no one was paying attention.
For the most part, and throughout most of history, election fraud on a massive scale has been hard; it requires very public actions or a highly corrupt government — or both. But electronic voting is different: a lone hacker can affect an election. He can do his work secretly before the machines are shipped to the polling stations. He can affect an entire area’s voting machines. And he can cover his tracks completely, writing code that deletes itself after the election.
You can even do away with the electronic vote-generation machines entirely and hand-mark your ballots like we do in Minnesota. Or run a 100% mail-in election like Oregon does. Again, paper ballots are the key.
Paper? Yes, paper. A stack of paper is harder to tamper with than a number in a computer’s memory. Voters can see their vote on paper, regardless of what goes on inside the computer. And most important, everyone understands paper. In today’s world of computer crashes, worms and hackers, a low-tech solution is the most secure.