A Princeton University computer science professor added new fuel Wednesday to claims that electronic voting machines used across much of the country are vulnerable to hacking that could alter vote totals or disable machines. In a paper posted on the university's Web site, Edward Felten and two graduate students described how they had tested a Diebold AccuVote-TS machine they obtained, found ways to quickly upload malicious programs and even developed a computer virus able to spread such programs between machines. About 80 percent of American voters are expected to use some form of electronic voting in the upcoming election. The AccuVote-TS is commonly used across the country, along with a newer model, the AccuVote-TSx. The machine Felten tested, obtained in May from an undisclosed source, was the same type used across Maryland in its primary election Tuesday, according to Ross Goldstein, a deputy administrator with the state's Board of Elections. Felten and graduate students Ariel Feldman and Alex Halderman...say they designed software capable of modifying all records, audit logs and counters kept by the voting machine, ensuring that a careful forensic examination would find nothing wrong. The programs were able to modify vote totals or cause machines to break down, something that could alter the course of an election if machines were located in crucial polling stations.