Plans for campaign finance reform often propose full disclosure of donations. But some legal experts have proposed that if all donations were totally anonymous, there would be no way to buy or sell influence. Computer scientists Matthew Franklin of the University of California, Davis, and Thomas Sander of InterTrust Technologies, Santa Clara, Calif. have come up with a cryptographic scheme to achieve just that.

Anonymous donations were proposed by law professors Ian Ayres of Yale University and Jeremy Bulow of Stanford University in a 1998 article in the Stanford Law Review. They argued that if candidates did not know who donors were, they could not sell access or influence. At the same time, anyone could say they had donated money, so nobody could be coerced into giving.

Ayres and Bulow proposed using blind trusts to make donations anonymous. But this would still be vulnerable to cheating, Franklin said. Instead, he and Sanders devised a computerized scheme that would scramble the identity of the donor. Candidates would get a regular update of their donation funds, but would not know where the money had come from -- or where to direct their thanks.

"The basis of the cryptographic solution is to make sure that participants can lie convincingly," Franklin said. Donors could not be coerced into giving, because they could unscramble the transcript of their donation to claim, plausibly, that they had given money to one candidate when in fact they had given to another.

It's also possible that donors could have someone stand over them in the donation booth, Franklin said. To avoid this, donors could undo coerced donations before making a final selection, he said.

Similar principles of security, privacy and deniability applied to electronic voting, said Franklin. The principle of secret balloting is that voters can avoid intimidation by claiming to have voted for any candidate. An electronic voting scheme of this type has already been tested in an election in Sweden, Franklin said.