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PGP disk, a security product by PGP Inc., which was recently acquired by Network Associates, solves the problem of data protection. It lets you create encrypted disk volumes on your PC that appear as just another drive. You can store, copy and delete files and folders from these volumes just like you can with any other volume. However, the data within, including all folders and files, are completely inaccessible without PGP disk and your pass phrase. When not being used, the volume is stored in an encrypted file.

Unlike other security products that protect single files or directories, PGP disk operates on encrypted volumes. Although it doesn't have centralized administration, it can be a great corporate tool because of its extreme ease of installation and use.

Protecting Your Data I tested a beta of PGP disk version 1 for Microsoft Corp. Windows95 version 1 in Network Computing's University of Wisconsin lab, installing it on an AMD K6 200-MHz computer with 9 GB of Ultra DMA EIDE drives and 64 MB of SDRAM memory.

After I finished the installation--which took only a few minutes--I created my first PGP disk volume. Volumes can be as small as few kilobytes or as large as 2,000 MB. The PGP disk volume cannot span multiple hard disks, however. PGP disk handles both FAT16 and FAT32.

After I created my first PGP disk volume, PGP disk asked me to enter a pass phrase to encrypt the volume. Next, the program mounted the encrypted volume, letting me assign a drive letter. PGP disk fully integrates with Windows Explorer, including right mouse clicks on files, and it associates the program with its extension. I also used a DOS window and saved to the volume from applications without a single glitch. I even formatted the volume using Windows format and PGP disk still worked like a charm.

Once I was done, I dismounted the volume, rendering it inaccessible. I also used some options that let me dismount my volumes automatically after a certain period of inactivity.

PGP disk protects data with Entrust Technologies' CAST encryption algorithm, one of the fastest and most secure algorithms available, at an impressive 128-bit key length. It clears pass phrases from memory, concealing them from view when, for example, virtual memory is used.

I first tested basic functionality and created several PGP disk volumes of various sizes. Then I began some more rigorous testing by reading, writing and copying to the PGP disk volumes simultaneously. Performance really impressed me, considering that real-time encryption was taking place.

Afterwards, I pushed the software to the limit. By running disk scan utilities while accessing PGP disk, I managed to crash Windows twice but didn't lose any of my data on the PGP disk volume. After rebooting, PGP disk notified me that my volumes were not mounted cleanly.

One drawback: PGP disk should have the ability to dynamically resize a PGP disk volume. Once a volume was created, the only way to increase its size was to create another bigger volume, copy the contents of the first volume to the second and delete the first volume. In addition, PGP disk doesn't work with disk-compression utilities.

Ahmad Abualsamid is a software development lead at Epic Systems Corp. He can be reached at sami@maf.wisc.edu.