USB flash drives are very small, very portable, very convenient -- and very easy to lose. In fact, the question to ask these days isn't how to avoid losing your flash drive, but how to make sure your data is safe when you do. As a result, Computerworld decided it was time to look at seven USB flash drives that are outfitted with security features to keep your data safe. (Compare Data Leak Protection products)

We did what most IT managers and users would do and asked some of the top vendors for their most secure USB flash drives. All but one of these products use some form of the Advanced Encryption Standard (AES) encryption, either 128-bit or 256-bit (according to experts, there's not much of a difference between 128-bit and 256-bit levels of AES encryption for ordinary purposes, as neither has yet been broken).

There was some variation in the implementation of the encryption on these drives -- some use AES keys derived from a user's password, while others use encryption keys generated by a hardware-based random number generator. (For more information, see our sidebar About Encryption .)

Our three reviewers -- Bill O'Brien, Rich Ericson and Lucas Mearian -- did not test the encryption algorithms themselves (that's a subject for another article), but did test the drives' performance, I/O rates, and CPU utilization. The reviewers also looked at the drives' security features, price, ease of installation, and ease of use.

Each device was tested for speed using Simpli Software's Hd Tach 3.0 . Interestingly, the reviewers came up with a wider range of performance numbers than anyone actually expected.

In fact, this turned out to be a very diverse group of drives with features ranging from secure and unsecure data partitioning, to waterproof, stainless-steel cases, to support for passwords of up to 99 characters. In every instance, there are different levels of ingenuity that went into the creation of these handy, very mobile devices, even if the level of protection varies.

This is by no means the definitive list of all the drives available -- only some from the largest vendors and the most highly advertised. There are many types of secure USB drives out there, including those using fingerprint scanning technology (we'll visit those in a later review).

In choosing a secure USB flash drive, you may have to first decide the relative importance of security, price, and speed, and compromise among those three factors. But in the end, we found that one drive stands out above the others.

1. Corsair Flash Padlock

The Corsair Flash Padlock is a horse of a different color from the encrypted drives in this roundup. This device is the same conceptually as the gear that kept your high school locker free from prying eyes -- a combination lock. It's strictly physical security, no encryption.

The Padlock looks like a traditional flash drive with a pull-off cap, except for the numeric keypad down the front. The keypad consists of five numbered buttons, while a sixth has a "key" icon. It's your entry point to accessing the security features of the drive.

As shipped, the Padlock is unlocked and can be used as a standard flash device. If you want to protect your data, you'll need to follow the instructions in the 17-page user manual (it's in six languages).

Security features

Setting up the drive involves pressing the key button, entering your selected PIN through the keypad, pressing the key button again, re-entering your PIN, followed by pressing the key button one last time. It's redundant grunt work with a few five-second time limits to make things tricky. Corsair recommends at least four digits, but the drive allows up to a 10-digit PIN.

After you've done that, you have 15 seconds to plug in the drive or it will automatically lock. However, if that happens, you'll just need to re-enter your PIN again to unlock it. If you don't unlock the drive, your computer won't recognize it at all, for anything. There's no need to lock the padlock once you remove it from your PC. It will do that itself after a few seconds.

What happens if you forget your PIN? If you register your PIN at Corsair's site you can retrieve it from there. If you didn't -- well, the Padlock is relatively inexpensive, so you can probably afford to buy another, since the one you have is now useless.

You can also change your PIN or totally unlock the drive if you no longer have a need for its security.

Speed, pricing and the bottom line

According to Hd Tach, the Padlock has a burst speed of 15.9MB/sec. and an average read rate of 15.4MB/sec. Both are rather slow, and although there was no discernible difference during music or video playback, it did take four times longer to get an 888MB video onto the Padlock than it did onto Corsair's Survivor.

I found the 1GB model on PriceGrabber for $27-$39 .

The key feature of the Corsair Flash Padlock is the lack of any software whatsoever. That means there is no AES encryption, but it also means the Padlock is compatible with Vista, XP, older versions of Windows, Linux, and yes, even Mac OS X. If you don't want or need the cross-platform versatility, or aren't comfortable with a keypad and a drop of glue standing between your data and the outside world, select one of the faster and more secure drives in our roundup. --Bill O'Brien

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