Electronic voting systems are supposed to be an alternative to the troublesome punch-card ballots. However, computer security experts say there are "significant security flaws" in the system that's being used in some states.

Researchers say the system designed by Diebold Election Systems is vulnerable to unscrupulous voters, insiders such as poll workers and even janitors.

The study says the problem is a "smart card" that's used in the system.

Voters use the ATM-like card to cast ballots. But researchers at Johns Hopkins University's Information Security Institute say voters could easily bring counterfeit cards to polls and cast multiple votes.

Lead researcher Avi Rubin said "there is no quick fix."

The institute also said that computer scientists have been warning of the perils of the systems, but vendors have forged ahead with their products.

A Diebold spokesman said the company needs more time to review the study. However, Mike Jacobsen said his company's systems "pass rigorous certification tests" at the federal and state levels.