The fingerprint scanner works by taking a mathematical snapshot of a user's unique biological traits, communicated through the loops and swirls of the fingerprint. These characteristics are identified as minutiae and are converted via proprietary algorithms into a string of data that can be transferred, encrypted (if necessary) and stored in a user database. The string represents a unique identifier that only one user can possess. Each device vendor has a different technology to handle this process, and the functionality and ease of use for your device is based on this and how the software vendor integrates the device for enrollment and authentication.

There are several key issues to consider when choosing a fingerprint scanner. Up front, it is important to stress that many of the vendors of the products we tested on the user-management end support specific devices from a few select vendors. Start by determining what devices are supported by the management system and the options that are best for your environment and needs. Cost is always an important consideration as you determine the number of biometric authentication devices you'll need. Remember that each system we tested will let passwords be used, and others (Indenticator Technology's BioLogon, for one) provide support for specific smart-card solutions.

Each device we worked with required an open port on our test machines. The majority of devices plugged into our parallel port. ABC's BioMouse allowed a pass-through to our parallel port, but models from Keytronics and Veridicom took the whole port for the device. Each device we tested requires a power input to operate. Some drew phantom power from the keyboard port, while others required a separate AC line. As you might expect, each product adds another cable or set of cables to the desktop and occupies a footprint about the size of a mouse. If space and cables are a concern, Cherry, Keytronics and other vendors offer an integrated keyboard-scanner solution.