(Wired) LOS ANGELES — Internet services company Yahoo Inc. on Friday said it is working on technology to combat e-mail spam by changing the way the Internet works to require authentication of a message’s sender. Yahoo said its “Domain Keys” software, which it hopes to launch in 2004, will be made available freely to the developers of the Web’s major open-source e-mail software and systems.

Spam — unwanted Internet e-mail, direct advertising, body part enlargement, and other commercial endeavors on the Web — has quickly become Web surfers’ Public Enemy No. 1 as inboxes around the globe are clogged with hundreds of such messages daily.

Governments around the world are working on legislation to reduce spam, but in the interim a number of companies have stepped in with technology proposals designed to filter and block the electronic detritus.

Under Yahoo’s new architecture, a system sending an e-mail message would embed a secure, private key in a message header. The receiving system would check the Internet’s Domain Name System for the public key registered to the sending domain.

If the public key is able to decrypt the private key embedded in the message, then the e-mail is considered authentic and can be delivered. If not, then the message is assumed not to be an authentic one from the sender and is blocked.

“One of the core problems with spam is we don’t know, Yahoo doesn’t know, the user doesn’t know … if it really came from the party who it says it came from,” Brad Garlinghouse, vice president for communication products at Yahoo, told Reuters. “What we’re proposing here is to re-engineer the way the Internet works with regard to the authentication of e-mail.”

While it might seem that Yahoo would need essentially all of the world’s e-mail systems on board with Domain Keys for it to work, Garlinghouse said the technology would work if even a few major providers adopt it.

“If we can get only a small percentage of the industry to buy in, we think it can have a dent,” he said.

Andrew Barrett, executive director of the SpamCon Foundation, an anti-spam organization, said Yahoo’s sheer size in online e-mail would give the technology a boost.

“The fact that Yahoo, one of the four big players in the space, is making it happen gets it a long way there,” he told Reuters. “It’s a great tool to have in the toolbox.”

Garlinghouse also argued that Yahoo’s proposal should be attractive to other e-mail providers because it is free and comes with no special restrictions.

“You look at a lot of the proposals for spam management out there (and) they king-make,” he said. “Are we trying to propose something that benefits us disproportionately? Not at all.”

SpamCon’s Barrett cautioned, though, that implementation would not be without its costs.

“It’s a good approach for those that are willing to use it,” he said. “Any kind of cryptographic solution is going to involve some computing overhead, and that’s not cheap.”