Hey, hackers! Wanna steal my credit card number? I'll save you some time. It's 4264-6553-2876-6583. That's a valid account, so be my guest. The problem (if you're a thief, at least) is that the account has a limit of $1 and expires this month. I may not be impervious to bad guys intent on purloining my credit card number--or my identity--but I've learned how to throw some obstacles in their way.

Although I like buying online, I'm squeamish about using my credit card. What if a sleazy merchant reuses my credit card number? Even when I'm dealing with a reputable seller, the number could be intercepted on the Internet, or the merchant's servers could be hacked. My unease has led me to experiment with credit cards that use one-time numbers. And I'm tickled with the way they work.

The concept is brilliant: Each time you shop, your credit card provider assigns you a unique, disposable number that's silently linked to your credit card account. Many credit card companies offer this type of service for free. I use MBNA's ShopSafe single-use credit card--not because it's better than the competition, but because I've used the company's card for a decade.

Secure Shopping

To use ShopSafe I simply downloaded and installed a small program that generates the single-use number. Now when I'm ready to buy something, I load the program, generate the number, and drag it to the online store's order form. I can even drag my shipping and billing information a line at a time if I wish.

The beauty of single-use numbers is that I also specify the amount of money and an expiration date. Let that sink in for a minute. I can limit how much of my dough the online store is able to get, and how long it can take to cash in. If an online merchant--or a hacker, for that matter--tries to take more money or use more time than I've allotted, the credit card company simply rejects the charge.

Just as risky as online purchases (or maybe more so) is buying by phone with a credit card. So why not use ShopSafe? There's no reason not to take advantage of the service all the time. Merchants needn't do anything special, and they don't have a clue it's a one-time number. And you maintain your right to dispute a payment if the product is unsatisfactory, or if the order is incomplete or incorrect.

One quibble: The ShopSafe software unnecessarily sticks an icon in the system tray. See a short tutorial on how to remove the icon and to see two images of the software.

Ask your credit card company or your bank if it offers similar free services. A few good places to start include Discover Deskshop, MasterCard's e-wallet, and American Express's Private Payments.

Self-Defense

I like my identity, and I take steps to keep it safe from thieves. For instance, I refuse to give out my Social Security number willy-nilly. This isn't easy: Even my cable company asks for it. For more on your SSN rights, visit Chris Hibbert's FAQ.

Opting out of receiving unsolicited, preapproved credit offers by mail is essential. If the letter falls into a thief's hands, you may be liable. You can't do it online--call the toll-free number set up by major credit bureaus to opt out at 888/567-8688. For details, read the FTC's Consumer Credit File Privacy alert.

If (heaven forbid) you ever find yourself a victim of identity theft, check out the Identity Theft Resource Center. There you'll find links to the three major credit reporting agencies, as well as tests to determine whether you and your business are doing everything possible to keep your identity safe. And on the Privacy Rights page you'll find great fact sheets on protecting your identity. Just don't tell them who sent you.

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