Easily portable storage devices have existed since the floppy diskette. These led on to Zip disks of various capacities and there were various competitors to that. Once CD burners became readily available CDs entered the fray. Storage capacity has been a problem as large PowerPoint presentations or other media files can exceed 500MB in size, even 750MB. That means CDs are no longer good enough. DVD drives are becoming cheap to replace them and probably soon be.

That solves a capacity problem but not security. Portable storage media rely on the device they are plugged onto being secure. They have had, until now, no in-built security. Small portable devices can also be lost, hence the use of key rings or pen clips to help avoid this happening.

There must be any number of keyfob USB storage devices, so-called thumb-drives, that have been mislaid. They use flash memory and capacities have been climbing over recent years; from 32 MB to 64, 126, 256 and now 512MB. We are now seeing 1GB capacity thumb-drives. They use a USB connection and so don't need a driver. They are also just as insecure as the old-style floppy disks. You just plug them into a USB port and the contents are available to everyone.

Secure thumb-drives
This means they are next to useless for professional or enterprise use with sensitive data. M-Systems has introduced one with password-protection. It is called DiskOnKey and comes in the now-standard format with a key ring and pen-style pocket clip. The drive does not actually come with the software needed to supply the pasword protection.

It's necessary to point your browser to www.diskonkey.com and download it. The software is called KeySafe and comes in Zip or compressed folder form. You double click on KeySafe and the software is installed. First you have to enter a password, repeat it and then enter a hint, to prompt you if you forget your password.

Then you can adjust a slider bar to set the amount of private, password-protected memory on the 1GB capacity device. Once that is done then you can drag and drop files into its folder on the desktop. Non-password protected files go in the open area. Password-protected files go in the closed area. When the device is plugged into another PC the closed area files are not visible in the device folder. The open area files are visible along with a white kangaroo icon on a red background.

Double click on that and enter the password, There is a short pause and then the private area files are shown plus a logout icon. It is not as if you get to see a sub-folder in the standard Windows file. You cannot see both the open zone and private zone files simultaneously. Also you cannot alter the size of the private zone without re-formatting the device and thus wiping out its stored data.

There is one other weakness with the device. Anyone stealing it can download the KeySafe software, enter a fresh password to be set, and then reformat the device thus deleting all the data on it. It's better than the private data being openly available though.

The KeySafe software takes advantage of an ARM 32-bit processor on the device. It's not that fast but it is better than thumb-drives without it, much better.

It's possible to use this CPU to do more. For example, Key Computing’s (an M-Systems company) Xkey version of the device incorporates a database, applications server, Exchange client and a cryptographic engine. When attached to an on-line computer, Xkey synchronises directly with the Exchange Server and everything that users do with Xkey is reflected automatically in Outlook for them to see when they return to the office.

Xkey contains the user’s key data – emails, calendar and contacts – as well as the necessary programs to connect to the user’s Microsoft Exchange server and to send and receive data securely. All a user need do is plug Xkey into their home PC, enter their PIN and begin working securely. This set up is okay for workers needing to work at home but who don't jusify a laptop.

Optical disks
You can use mini-CDs but these things are, by present day standards, tiny. A mere 202MB is not a lot. DVDs are becoming common and it's probable that in a couple of years they will have replaced CDs for data exchange. Until then you can't rely on a PC at a location you are visiting having a DVD drive. It will have a USB port though.

Fujitsu has launched a pocket magneto-optical drive. This is called the DynaMO 1300 U2 Pocket. It has a 1.3GB capacity and a USB2.0 interface. Power comes to the drive via that.

In common with DiskOnKey not all USB ports you meet will deliver enough power. Keyboard-located ports, for example, tend to be insufficient. It all depends upon the desktop machine's power supply unit and the number of used and operational USB ports. There is no easy way of finding out if power is sufficent, other than plugging the device into a socket. This arrangement is, it has to be said, rather amateur.

Fujitsu's pocket MO device is larger than the DiskOnKey unit but, with a 3.5inch form factor, will fit in a jacket pocket. It weighs around 400gm and costs around £130. (THis is lighter than an exterernal DVD drive, and smaller.) Drivers are shipped with the device. This device is a Ronseal-type device. It does what it says on the tin; provides 1.3GB of pocket storage.

But there is no security. As disk and drive come as a unit then anyone could steal one, plug it into a pC and view all the files on it. It is just not very secure. For closed and secure office or institutional environments then the pocket MO disk/drive has a good capacity, better than DiskOnKey. For insecure environments DiskOnKey gives you that extra level of security.

At a price though. DiskOnKey costs around $232 in the USA, which is a £130 at a straight conversion. Expect to pay more than this though, particularly if it comes with software like the Xkey.

For bulkier pockets
It's possible to buy external USB-connected hard drives that hold vastly more than either the pocket MO disk from Fujitsu or DiskOnKey. Forty gigabytes or greater capacity is readily available and USB connection the norm. Price per GB is much less than Flash memory or M-O disk/drive units.

If 1GB is not enough, but 40GB far too much, then wait a few months. There has been a steadily reducing cost/MB of flash memory. We can reasonably expect 2GB devices in 2005 and 4GB ones thereafter.

If you need small size and light weight then Fujitsu's M-O device is pretty good. But if you need that and security then DiskOnKey has the edge.