Hands Off! Personal Computer Privacy

Don't Erase: Encrypt!

Protecting the security of files you want to keep on your computer is another matter altogether, of course, and plain vanilla password protection through your screen saver or boot screen is not a real deterrent for the determined snoop.

Good encryption and locking solutions for the home user are increasingly user-friendly, inexpensive, and almost impossible for snoops to hack. Even the Government recognises this and is on the verge of requiring users who are suspected of using their computers to commit crimes (or of irritating various and sundry Government security agencies) to hand over encryption keys when computers are seized.

Security that tight should defeat casual efforts at intrusion completely -- and if encrypted files are left on a re-sold computer, they won't be readable outside a very advanced laboratory (there are always residual traces of the pre-encryption data that can be extracted under extreme recovery conditions) .

One of the best encryption tools is Kryptel, which actually encrypts both file contents and passwords using "strong" cryptographic algorithms, for $US40.

There are also, unfortunately, more than a few toy approaches to file security that abuse the term and offer what is more simple disguise than actual encryption.

Some tools, like Webroot's PrivacyMaker, work by hiding files -- including Internet activity -- except by session access through an encrypted password. As Windows users can already make any file invisible, what's added here is akin to a deadbolt on a flimsy door.

Another "encryption" technique in common use involves renaming the file extension so that it can be accessed only through the encryption software (e.g., a *.doc file becomes a *.cv4 file). Once a snoop knows the file extension, she or he can easily rename the file and it will then open in the original application.

Wiping Doesn't Work...

Ultimately, however, wiping is unlikely to provide full erasure of data, no matter how many times a file is written over. The reasons for this are arcane, but the proof is in the pudding.

A recent analysis by Ziff Davis' (ZDNet) eTesting Labs of nine market leading wipe tools showed that only one worked well in every case -- and that product was supplied by the company that commissioned the study. IBAS ExpertEraser failed to completely wipe data from only one of the six computers in the study, however, so short of smelting the hard drive, this may be your best bet at only 28 euros for a one-shot license. Just be sure you mean it.

Redemtech Data Erasure: www.redemtech.com

For a technical overview of the sticky memory problem, see "Secure Deletion of Data from Magnetic and Solid-State Memory", by Peter Gutman of the University of Auckland, 1996.

See also this Slashdot archived discussion of how to fully wipe a hard drive. Their conclusion? Drop it into the sun.

Covering Your Tracks

Securing your files and wiping your hard drives are critical capabilities, but what if you just want to cover your tracks?

Simple as. When snoops want to find out what you've been up to, they look in all the likely places first -- and often, last. While a computer forensics expert won't be put off by such basic housekeeping, at least your spouse won't find out that you've been shopping for diamonds if you tidy up after each surfing session.

Internet Cache

The first place to start is with your surfing history and your cached Internet files. Both can be cleared in Internet Explorer from the Tools button. Netscape Navigator lets you do this from the Preferences file.

Neither browser always deletes all cache content, however, and Windows Explorer is a handy system tool to locate errant cache files (look into every file that says Temp, to start) for manual deletion.

Cookies

Then, cookies. Many Websites set little text files on your computer every time you visit. These are usually harmless -- often the sites use them to personalise presentation, or to keep track of your shopping cart. They do, however, contain in plain view the address of setting Websites and other information you might not want anyone to see (like what you bought during your visit).

To view them, go to your Start button and use the search tool to find a folder called Cookies. You can delete any of these cookie files -- or all of them. Advanced browsers also let you manage incoming cookies before they take up residence on your computer by notifying you that a cookie is being set and asking for permission.