Any programmer can write code that displays one thing on a screen, records something else, and prints yet another result. There is no known way to ensure that this is not happening inside of a voting system. Hence, no current electronic voting system has been verified as secure. Electronic balloting and tabulation makes the tasks performed by poll workers, challengers, and election officials purely procedural, and removes any opportunity to perform bipartisan checks. Any computerized election process is thus entrusted to the small group of individuals who program, construct and maintain the machines.
Encryption provides no assurance of privacy or accuracy of ballots cast.
Cryptographic systems, even strong ones, can be cracked or hacked, thus leaving the ballot contents along with the identity of the voter open to perusal. One of the nation's top cryptographers, Bruce Schneier, has recently expressed his concerns on this matter, and has recommended that no computer voting system be adopted unless it also provides a physical paper ballot perused by the voter and used for recount and verification. Furthermore, this form of voting does not provide equal access for convenient balloting by all citizens, especially the poor, those in rural areas not well-served by Internet service providers, the elderly, and certain disabled populations. For these reasons, off-site Internet voting systems should not be used for any government election. It is a known fact that the computer industry does not have the capability, at present, to assure a safe, reliable election using only electronic devices.