On the Web you sense that you're invisible. That probably is what David L. Smith thought. But the young geek charged with creating the Melissa virus was wrong.

Smith didn't know that Microsoft, whose office software has 100 million users worldwide, embeds a unique numeric identifier into every copy of Office 97. This ID puts a watermark on every Microsoft Office document created with this software. So when Smith surfed the Web, he left behind his code--and in essence his name. Authorities nabbed him by matching the code found in the virus to documents he had posted to a Web site frequented by virus makers.

So Microsoft may know who you are--and so might every Web site you have ever flitted past. That's the point of "registrations" for such "free" services as e-mail and personal home pages; that's part of what inspires "cookies," the electronic eavesdroppers that track your every move to let the site serve you better (and market to you better, too).

"A profile could be created of every site a user visits, and that could be linked to that user's real-world identity--all without the user's express permission," says Barbara Bellissimo, chief executive of Privada, a Web site (www.privada.net) offering anonymous Web surfing. "Imagine a record being made of every time you walked into a store and looked around, and every time you walked by a store window and merely stopped to look at it."

Steps to safeguard your identity in cyberspace:

• Don't give out personal information to a Web site unless it has a satisfactory privacy policy. Alternatively, make up a fictitious persona for use on-line.
• Consider going through sites like anonymizer.com, which at least profess to let you surf the Net in anonymity.
• Use a free e-mail account at a site like excite.com as your return address for commercial dealings and don't worry that it may fill up with junk. Save a private account for friends.
• Create multiple profiles, each tailored to the type of site you visit and your activity there.
• Don't send anything confidential in unencrypted electronic messages.

The CIA's favorite spy in the sky now sees better than ever, thanks to a small radar imaging system that peers through clouds.

Generally acknowledged as one of the CIA's key intelligence-gathering tools, the I-Gnat is an unmanned plane made in the U.S. The 18-foot-9-inch-long plane, with a wingspan of 42 feet, was used to monitor Serbian troop buildups during the recent war in Kosovo. It also observed terrorists who took over the Japanese embassy in Peru in 1997, say aviation experts.

These monitoring activities should be even more effective in the future, now that the I-Gnat is equipped with a new 115-pound synthetic aperture radar, dubbed Lynx, that has a resolution of 4 inches. By comparison, the famous U-2 spy plane produces recognizable images of objects 1 to 3 feet in size. And spy satellites, which reportedly have an imaging resolution similar to Lynx, are limited in their response time.

Synthetic aperture radar has been in existence for years, but it has never before been so small, lightweight, and sensitive. Lynx produces photolike images day or night--through clouds, fog, or rain at a distance of up to 16 miles, from an altitude of 25,000 feet. Under ideal conditions, Lynx's fine resolution even enables it to detect footprints on soft terrain like sand or mud.

The $180 billion merger between America Online Inc. and Time Warner Inc. created one of the largest databases ever, teeming with juicy information about individual tastes in books, music, magazines, as well as hobbies.

Marketers are salivating about how the companies could combine their data and use it to send targeted advertisements and promotions that will entice people to spend more on AOL-Time Warner offerings as well as products from other advertisers. But the prospect of a massive database also has some privacy experts worried about its appeal to Internet hackers as well as potential for misuse by marketers.

"It is a nightmare," says Jason Catlett, president of Junkbusters Inc., a consumer-privacy group.

AOL already has the names, addresses and credit-card numbers of its 22 million members. It also has tons of tidbits on ages, interests and musical tastes of the people who fill out member-profile pages or register with AOL's ICQ chat or its Spinner online radio divisions.

Meanwhile, Time Warner has the names, addresses and information on the reading and listening habits of the 65 million households who receive its magazines, CDs and books.

"They'll have one big honey pot of information about a person," said Catlett of Junkbusters Inc. "It will be a magnet for government investigators, for hackers and for misuse by marketers."

Israeli researchers have discovered design flaws that allow the descrambling of supposedly private conversations carried by hundreds of millions of wireless phones. Alex Biryukov and Adi Shamir described how a PC with 128 MB RAM and large hard drives can penetrate the security of a phone call or data transmission in less than one second. The flawed algorithm appears in digital GSM phones used by well over 100 million customers in Europe and the United States.

Visions of stealthy black helicopters landing on your lawn and disgorging troops to steal your PGP keys aren't just for conspiracy theorists. The Clinton administration wants to be able to send federal agents armed with search warrants into homes to copy encryption keys and implant secret back doors onto computers.

"When criminals like drug dealers and terrorists use encryption to conceal their communications, law enforcement must be able to respond in a manner that will not thwart an investigation or tip off a suspect," Attorney General Janet Reno and Deputy Defense Secretary John Hamre wrote in a seven-page letter to Congress.

The idea first surfaced in mid-1999, when the Justice Department proposed legislation that allowed them to obtain surreptitious warrants and "postpone" notifying the person whose property they entered for 30 days.

The Justice Department's thinking was that if a suspect was using data-scrambling encryption products, the FBI's G-men might need to enter the suspect's home and install software to tap into and decipher scrambled communications.

After vocal objections from civil liberties groups, the administration backed away from the controversial plan. But the White House now appears to think it doesn't need new legislation to enter a suspect's computer.

The letter from Reno and Hamre to House Majority Leader Dick Armey says that, in the future, the Feds will use "general authorities" when asking judges to authorize so-called black bag jobs. They say that law enforcement should have the ability to "search for keys" without immediately notifying a suspect.

According to legal experts, all current search warrants--with the exception of the related category of wiretaps--require police to inform the person his property was entered.

Privacy groups say Americans should be alarmed. "What they're saying is that they want to eliminate that Fourth Amendment requirement or limit it so much to make it meaningless," said Dave Banisar, co-author of the Electronic Privacy Papers. The Fourth Amendment prohibits the government from conducting "unreasonable" searches and seizures.

Every Australian farmer will be monitored by satellite by May 1 in an agricultural revolution that is changing the face of global food production.

Canberra-based company Agrecon is behind the move to monitor every square meter of farming land in the nation. Land owners will be told via the Internet how productive their property has been over two decades. Farmers will be updated on everything from crop yields to temperatures and rainfalls.

The Agricultural Monitoring System (AMS) is part of a satellite-led agricultural revolution which will see international surveillance satellites operating by the end of the year. They will monitor our global trading competitors, identifying crop performances to give Australian commodities a leading edge in the international marketplaces.