How can I keep data on my laptop secure?

Home » General Computing

Summary: Laptops are portable, convenient and easily lost. When lost all the data could easily be available to the finder. Encryption is the answer.

I know how you feel. I, too, have sensitive information on my laptop that I would prefer not to fall into the wrong hands. I can handle losing the laptop, but the thinking about the data in the wrong hands ... well, it just gives me the willies.

So, yes, I do have a solution, and it turns out to be fairly easy, secure, and free.

•

Now, naturally, you can "encrypt" your data using a simple tool like WinZip and assigning the resulting archive a password. The problem is that it's fairly easy to crack the zip file's password, and get at the data. It has its uses, though. Much like a cheap padlock, it's mostly about keeping honest people honest.

I recently started using something called TrueCrypt. TrueCrypt is free, open source, on-the-fly encryption software. It provides serious industrial-strength encryption while still being fairly easy to use.

TrueCrypt can be used in several ways, the two most common are that it can encrypt an entire disk volume - such as a USB thumb drive, floppy disk, or an entire hard disk if you like - or, it can create an encrypted virtual disk. It's this later approach that I like to use.

An encrypted virtual disk is simply a file that TrueCrypt "mounts" as an additional drive letter on your machine. You specify the pass phrase when the virtual drive is mounted and thereafter everything you access from there is automatically DEcrypted and anything you place there is ENcrypted.

For example, you might have TrueCrypt create an encrypted drive as c:\windows\secritstuf. If someone were to look at the contents of that file directly, they would see only random gibberish - the result of encryption. When using TrueCrypt to mount that file as a virtual drive, (for example selecting the drive letter "P:") then P: would look and operate like any other disk, and would contain the contents of the encrypted drive. Encryption is as simple as moving a file to the drive.

The trick, then, is to never mount the drive automatically. When your machine boots up, "P:", for example, would be nowhere to be found, and the encrypted file c:\windows\secritstuf would be present, but only visible as gibberish. If someone stole your machine that's all they would find.

Only after you've used the TrueCrypt program to select the file (c:\windows\secritstuf), choose the drive to mount it as (P:) and supply the correct pass phrase, would the virtual drive be "mounted" and the encrypted data become accessible.

TrueCrypt supports a number of different high-powered encryption algorithms. The documentation for TrueCrypt is clearly targeting at the seriously paranoid, including instructions on how to maintain "plausible deniability" should a thief ever force you to supply a password. Let's hope that'll only be of passing interest to any of us.

Now, a couple of caveats:

• Encryption does not make a bad password any more secure. If you choose an obvious password or pass phrase, a dictionary attack can certainly be mounted that could unlock your encrypted volume.
• An encrypted volume does you no good if the files you care about are also elsewhere on your machine.
• That being said, make sure you have secure backups, updated regularly. Preferably keep them UNencrypted, but secure in some other way, in case you lose your encrypted volume or forget your password. Without the password, the data is not recoverable.
• That last statement is technically inaccurate. You should always be aware that things are never 100% secure. All encryption can, theoretically, be hacked. The purpose of encryption is to make the cost of that hacking so astronomical as to be impractical. For example, spending a calendar year on a brute force hacking attempt is kinda pointless to discover next month's sales forecasts. Similarly hiring the expertise required to attempt such a recovery might also be astronomically costly.

Data encryption is an important part of an overall security strategy. Keeping your sensitive data secure requires a little forethought and planning. With viruses and spyware running amok, not to mention the theft scenario that we started this article with, there's no excuse not to take that time, and save yourself some serious grief later if the unthinkable happens.

Related:

• TrueCrypt - Free open-source disk encryption

• Ask Leo! - How do I keep my computer safe on the internet?

• Ask Leo! - How can I keep my email safe from sniffing?

Article C2343 - April 28, 2005