Cryptography expert Bruce Shneier makes a compelling case for abandoning electronic voting and using only paper ballots, whether filed out by the voter or printed by a touchscreen laptop. His argument: it's just too easy to fix the vote without a paper trail.

Electronic voting is like an iceberg; the real threats are below the waterline where you can't see them. Paperless electronic voting machines bypass that security process, allowing a small group of people -- or even a single hacker -- to affect an election. 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.

This is both new and terrifying. 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.

I voted this fall on a touchscreen voting machine, but it's doubtful my precinct votecount was hijacked, and if it were, it was probably due to incompetence, since the results of the major federal elections in Mississippi were foreordained. There's no point in committing fraud and risking being caught when the election isn't close. When an election is close, however, all it takes is a few changed votes in a number of "safe" precincts, and the result can be changed without anyone being the wiser.
So read Schnier's article; even better, subscribe to his newsletter, the Crypto-Gram, in which he discusses security of all kinds almost always in non-technical language.