Jiang secretly had installed, in at least 14 Kinko's stores, software that logs individual keystrokes. He captured more than 450 user names and passwords, using them to access and even open bank accounts online.

The case, which led to a guilty plea earlier this month after Jiang was caught, highlights the risks and dangers of using public Internet terminals at cybercafŽs, libraries, airports and other establishments.

"Use common sense when using any public terminal," warned Neel Mehta, research engineer at Internet Security Systems Inc. "For most day-to-day stuff like surfing the Web, you're probably all right, but for anything sensitive you should think twice."

Jiang was caught when, according to court records, he used one of the stolen passwords to access a computer with GoToMyPC software, which lets individuals remotely access their own computers from elsewhere.

The GoToMyPC subscriber was home at the time and suddenly saw the cursor on his computer move around the screen and files open as if by themselves. He then saw an account being opened in his name at an online payment transfer service.

Jiang, who is awaiting sentencing, admitted installing Invisible KeyLogger Stealth software at Kinko's as early as Feb. 14, 2001.

The software is one of several keystroke loggers available for businesses and parents to monitor their employees and children.

The government even installed one such program to capture a password that the son of jailed mob boss Nicodemo "Little Nicky" Scarfo used to access files on his computer.

Earlier this year, a former Boston College student pleaded guilty to using similar software on more than 100 computers around campus to collect passwords and other data to create a campus ID card for making purchases and entering buildings illegally, authorities say.

Mehta said that while millions of individuals use public terminals without trouble, they should be cautious.

"When you sit down at an Internet cafŽ, ask the owner or operator about the security measures in place," he said. "If they don't know or don't have anything in place, you could consider going somewhere else."

Encrypting e-mail and Web sessions does nothing to combat keystroke loggers, which capture data before the scrambling occurs. But encryption can guard against network sniffers — software that can monitor e-mail messages, passwords and other traffic while it is in transit.

Data cookies also contribute to the risk of identity theft. Cookies are files that help Web sites remember who you are so you won't have to keep logging on to a site. But unless you remember to log out, these files could let the next person using the public terminal to surf the Web as you.

Furthermore, browsers typically record recent Web sites visited so users won't have to retype addresses. But such addresses often have user names and other sensitive information embedded.