Rapid advances in the development of cyberweapons and malicious software mean that electronic-voting machines used in the 2012 election could be hacked, potentially tipping the presidential election or a number of other races. [A University of Pennsylvania] study concluded virtually every important software security mechanism is vulnerable." Most at risk are paperless e-voting machines, which don't print out any record of votes. Four swing states - Pennsylvania, Virginia, Colorado, and Florida - rely to varying degrees on paperless machines. Alex Halderman, a researcher at the University of Michigan, and a colleague at Princeton University hacked into a paperless touch-screen voting machine in 2010 and installed the video game Pac-Man. Similarly, he and Princeton researchers in 2006 demonstrated that if someone could get a few minutes' unattended access to a paperless machine, that person could install a software virus that could spread to other machines and switch those machines' votes before deleting all traces of itself. Among the 23 states that use touch-screen Direct-Recording Electronic (DREs) machines ... only California, Indiana, and Ohio were rated excellent in a national report this summer by Verified Voting. For a savvy hacker, the time and access needed to infect a machine is so small that it could be done while in a voting booth. A hacker could in theory use the Internet to target an e-voting machine company, which would then unknowingly infect its own machines when it serviced them. It's impossible to know if newer machines and software are really secure because their source code is largely unavailable for analysis. Voting-equipment makers frequently say their software is a trade secret.