There is only one way that electronic voting can begin to be reasonable.
You have a piece of paper that accompanies each vote cast electronically, and as you cast your vote via the computer, a machine marks your paper vote for you, in a clear case so you can see it marking the ballot, which then gets dropped into a ballot box as normal.
Every one of these votes will have a uniq serial number, and that number must tally with the number of voters logged in the polling booth.
When a recount is needed, they ignore the electronic vote tally, and count the paper votes.
They also spot check machines randomly to make sure the machine agrees with the paper votes.
All other ways are vulnerable to attack and cracking, and can never be trusted. (Thats not to say that the above method is not vulnerable though.)
No paper trail == fraud.
You need 2 till rolls. One hidden from the voter and one visible under a glass screen. The hidden one records cumulative data and the individual one records each persons vote so the person can see what the computer has logged.
At the end of the day you pull out the cumulative printout and cross check this against what the computers memory has recorded - you check the cuml. number of voters against the personating officers logs and against the total number of votes cast on the visible till roll.
You can then keep the visible till roll and if necessary redo the count from that.