Internet privacy advocates alarmed by broad new surveillance powers given to the Department of Justice say it's only a matter of time before FBI cyberspying explodes to new levels — and they are looking at the mythical "Magic Lantern" as the next Trojan horse of e-spying.

Magic Lantern is the FBI's latest and most closely-guarded program designed to let agents track Web browsing activity, including e-mail and password access, without detection. While some experts say it is still in the planning stages, most techies believe it already operates.

Its existence, leaked to the press last December, enables agents to remotely bug a suspect’s computer and trace his or her movements online and offline by recording the keystrokes on the user's keyboard.

"It allows them to bug a computer in ways that in the past they were not able to do," said David Sobel, an analyst for the Electronic Privacy Information Center.

Magic Lantern may indeed have been in the planning stages up to now, but with the passage of the USA Patriot Act, signed into law last October, experts say there is nothing stopping the government from opening the trapdoor into individual and business computers.

"We generally think the Patriot Act is overreaching — it just goes too far," said a lobbyist from a major Washington D.C. law firm, who asked not to be named.

But supporters of the program say that Magic Lantern, often called a Trojan horse because the suspect doesn't know what's coming, is actually a better method for surveilling bad guys than a dragnet like Carnivore.

"With Carnivore you have a tool that a bad agent could use to do a dragnet search across the Internet for personal reasons. In this case, Magic Lantern is a one-to-one tool," said Richard Diamond, spokesman for House Majority Leader Dick Armey, R-Texas. "It doesn't seem to be more dangerous than a wiretap as long as it is approved by a judge under the proper guidelines."

Diamond said that the Patriot Act requires agents conducting Internet surveillance to keep detailed logs for the judge issuing the warrant that include information gathered, names of targets, and tools used.

The Patriot Act also demands that FBI agents get a warrant to use surveillance programs like Magic Lantern, much the way a warrant would be needed to enter someone's home. That's all good, say experts, except that the Patriot Act now makes it easier for law enforcement officials to get search warrants.

An FBI spokesman refused to confirm or deny whether Magic Lantern even exists yet, but said the bureau doesn't use any technology that isn't already available in hi-tech circles.

"We are not in any position to talk about this," said FBI spokesman Paul Bresson. "As far as what tools we use, we’re trying to keep pace with the rest of the world where technology is concerned and how it is advanced."

Of course, the technology is indeed widely available already. Online companies are hawking spy gear all of the time to parents who want to track their children's Internet use or to jealous spouses who want to read their partners' e-mail.

But for spymasters acting with the force of the law behind them, the story changes altogether.

"Magic Lantern certainly gives the federal government the ability to make creative use of the Patriot Act," said Sobel. "It’s not someone’s paranoid fantasy, there is the existence of such a thing."

Indeed, with the technology, agents now don't even need to leave the safety of their own offices to bug a computer. Magic Lantern can employ the use of an attached virus on an e-mail to target suspects.

Though a search warrant is needed before a bug is sent, Lee Tien, senior staff attorney for the Electronic Frontier Foundation, said that the surveillance issue does raise "constitutional questions."

"It can be argued that the use of this kind of device raises constitutional questions of the highest order," Tien said, adding that while a "vast majority" of users will never be touched by Magic Lantern, "there’s the potential for abuse, and this is the kind of technology that can be easily abused."