Answer Line: Keep Your Secrets: A Safe, Easy Way to Encrypt Files

Illustration: Harry Campbell

How do I encrypt files, and which ones should I encrypt?

Conrad Layne, Plain City, Ohio

Any system that encrypts your entire hard drive is overkill for most PC users. I prefer encrypted safes, which are files that contain encrypted folders and files. To the outside world, a safe looks like a big file filled with gobbledygook. Open a safe with its password, and you reveal a virtual drive holding your sensitive data. When you're done and you close the safe, the data reverts to gobbledygook.

Safes are easy to use, transportable from one PC to another, and a breeze to back up. I recommend the free open-source safe program TrueCrypt, which supports AES-256, Blowfish, Triple DES, and other heavy-duty encryption algorithms. TrueCrypt hides your safe well--if you're in the belt-and-suspenders crowd, it can even place your safe inside another safe.

Remember: No encryption is secure with an easy-to-guess password. Safest is a string of 20 or more apparently random letters and numbers. But how do you remember such a password?

Make up an easy-to-remember but impossible-to-figure-out formula of family names, birthdays, and memorable words. For instance, use your kids' names spelled backward, with every third letter capitalized, followed by your birthday squared--be sure, though, not to use a formula that has been printed in PC World. Click here for more tips on crafting secure passwords.

Write the password or the formula on a business card and carry it in your wallet. It's unlikely that someone will steal your wallet and your PC, and even less likely that they'll figure the card out.

What files should you put in the safe? Any that you don't want crooks, competitors, coworkers, or even your own children to see. One top priority is financial information, especially if it involves credit card, bank, or Social Security numbers. Passwords to retail Web sites should also be stored in the safe. You might put some sensitive work-related files there as well (although your IS department likely has an encryption policy). Your résumé , family photos, private e-mail, and other files that you want to keep secure and confidential are candidates for the safe, too.