"Nearly half of online consumers surveyed are adversely affected by security concerns that arise from the abundance of data breach disclosures in 2005 and 2006," Litan says. "Their behavior in the online world, as opposed to the physical world, is most affected."

In fact, Litan says, nearly half of adults in the United States who go online, about 46% of more than 155 million people, say they have changed their online behavior because of data theft and Internet and phishing attacks, with online banking, payments and shopping feeling the biggest impact.

Distrust of e-mail is particularly acute, Gartner researchers have found in their surveys. Nearly 70% of online consumers say their trust in e-mail from senders they don't personally know has been affected, and 85% of that group now deletes suspect e-mail without opening it.

While that's good news to security experts who have long advised doing just that to avoid online attacks, it's a problem for e-commerce.

"This figure has serious implications for banks and other companies that want to use the e-mail channel to communicate more cost-effectively with their customer base," Litan says in her report.

"For example, sending a bill electronically costs about half of what it costs to send that same bill through regular mail," she says.

Such realities have left credit unions, banks, the entire spectrum of e-commerce providers, looking for ways to lock down the channel while assuring consumers of its safety. One of the most secure is a token, an extra device that is attached to PCs and laptops. Gartner research found consumers divided in their willingness to use such tools. About 32% of all consumers would be "somewhat" or "very" willing to use such devices, the research and advisory firm says. Meanwhile, nearly 30% of consumers age 65 and older were "not at all willing" while identity theft victims were the most willing.

"This is to be expected," Litan says, "because most older Americans are not as comfortable with different technologies and devices as their younger peers, while identity theft victims become more protective of their information and activities and are more willing to take steps to prevent a recurrence."

The report reviewed consumer preference for a wide range of device types, including key fobs, detached password generators and even phone calls, and concluded: "Banks and other service providers are challenged to find an option that would be equally welcome by all their customer types." –[email protected]