Actually, I'd be perfectly content with optical scanners since their error rate is quite low, and they have been in use for a long time. Another advantage of scanners is that they don't have to be working in order to vote, all the voter needs is a pen to mark the ballot (a cheap enough device to have lots of spares on hand in case one breaks down :-). The scanners only need to be working to give the rabid news media the instant feedback they can't seem to live without. If a few scanners break down, it just takes a while longer to total the vote.
However, none of that seems to be able to convince elections supervisors that scanners are the way to go, so if we can't have scanners, let's see if we can't devise a sensible electronic voting system people can trust.
Speaking of trusting machines, here is page 229 from my 1968 paperback copy of Robert Heinlein's The Moon is a Harsh Mistress. Among the many other predictions of this visionary science fiction writer, you can see he also predicted electronic voting fraud.
There is very little about the following design that I'd consider original, but it does serve to indicate the direction we could go to increase confidence that the system works right.
My design has two machines. One prints ballots, the other accepts the printed ballots. Here's how the voting process works:
In addition to the procedures described above, the machines themselves need to operate with a strictly write-once media such as CD-R to record operations during the day and to boot the software initially. The CDR disks need to be digitally signed by the election supervisors office when preparing the initial content to run the machines, and signed by the machines themselves each time new information is recorded. With media that can't be accidentally erased or modified without detection, the results are much more likely to be accurate without resorting to counting the ballots by hand.
Once some folks with a lot more expertise than me improve on this design, I might be willing to trust it. I'd already trust it a lot more than the completely wide open "just trust us" touch screens we have today.
Having said all that, I'd still rather have optical scanners for the simplicity of pen and paper. Electronics always breakdown, usually at the most inconvenient times. With scanners, the election process is not at the mercy of finicky electronic equipment.
If we must have fancy electronic voting machines, we could at least get some additional benefit from them: I already mentioned randomizing the order of names and races for each voter. Another huge benefit would be the ability to eradicate all primary elections and all controversy about who should be able to vote in which primary.
It would be simplicity itself to enhance the electronic machines to allow you to arrange the candidates you'd be willing to vote for in preference order, so the primary and the general election could happen all at once. Just keep chucking out the candidate with the smallest total, and transferring his votes to the other candidates according to the voters preferences. Eventually you'll have the winner who the most voters expressed some measure of tolerance for :-).
And, of course, the biggest benefit of eradicating primaries would be eradicating the magnified voice the looney fringes (or "base" as they like to call it) have on the choice of candidates. Heck, after a few primary free elections, we might actually have a government of moderates dedicated to working together.