No single network security technology arouses passionate debate like  biometrics, which relies on authenticating identities by matching a person's body parts, voice or signature to grant access to computer resources or restricted building areas.

Proponents say authentication based on aspects of an individual's body - such as fingerprint matching or iris scanning - offers far better security than any based on re-usable passwords or hardware tokens that generate one-time passwords. "We've been doing large-scale ID systems for 12 years for [the Department of Defense] and the Department of State, and biometrics is a very compelling technology," says Tim Corcoran, senior systems engineer at Northrup Grumman's IT division.

"Biometrics is not ready for prime time," says Stephen Elky, security auditor at Software Performance Systems in Arlington, Va., which tested biometrics products under government contract.

But critics point out that biometrics can be expensive and invasive, and that none of the hundreds of biometric products on the market is infallible in pattern-matching a scanned body part to a biometric image. "It's all snake oil," scoffs Jim Kirby, network engineer at Wells-Dairy, pointing to a widely publicized experiment in Japan earlier this year that showed people could fool fingerprint scanners by using molded "gummy fingers" made of gelatin.

Biometrics believers

Despite the back and forth, biometrics continues to work its way into more environments.

A case in point is the U.S. government, which is poised to deploy biometrics on an unprecedented scale for improving security in the military, transportation industry and in border-crossing control. That could really give a boost to a market that has increased steadily, if not spectacularly - IDC analyst Charles Kolodgy says the market increased from $77 million in 2000 to $80 million last year and is expected to grow 15% to $92 million this year.

Northrop Grumman, which has worked with the U.S. Air Force and other parts of the Defense Department to install iris and fingerprint scanners, expects to see the U.S. government install hundreds of thousands or even millions of biometric products in years to come. The rollouts will be fueled in large part by mandates from Congress through the U.S. Patriot Act and the Bush administration through its homeland security efforts.