Electronic voting should be prohibited by law. It is too easy to systematically cheat and the ways to cheat are too numerous to list and limited only by one’s creativity.
So, we go back to the RATs in the back room of the union hall premarking hundreds of paper ballots, or prepunching stacks of butterfly ballot cards (Hanging and dimpled chads, remember?) or "finding" another box of votes in a car trunk once they learn how many they need, or losing boxes of votes from dependably conservative districts?
The machines in use in (our part of, at least) New Jersey are not connected to any internet or phone line. When the machine is turned on in the morning it prints out a "zero proof", showing the choices available and the votes for each, which should all be zero. At the close of voting it prints out the results. The total votes cast are matched up with the number of voters signed in by a voter authority slip for each.
The only way the machines could be "jiggered" would be in the warehouses in which they are stored between elections, each one individually. That would require a plethora of politically motivated or bribed technicians working full time in the off season. And SOMEONE would eventually expose it.