Emerging Technology: Digital Fingerprinting

Fingerprinting could be the best way to put cybercriminals under your thumb

By Steven Johnson
Oct 1, 2004 5:00 AMApr 25, 2023 7:30 PM


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Since the day Brandon Mayfield, a lawyer from Portland, Oregon, was released from federal custody after a fingerprint had linked him to this year’s Madrid terror bombings, a national debate has erupted over the scientific validity of fingerprint identification. Legal scholars and defense attorneys have been shocked to discover that almost no research has been done to confirm that everyone actually has different fingerprints. The problem is compounded by the fact that matching fingerprints to a specific person can be a matter of some interpretation. Coincidentally, just as fingerprints are being challenged within the judicial system, they are finding new life in the private sector. If a company called DigitalPersona has its way, fingerprints will someday become the preferred means of personal identification every time anyone uses a credit card or withdraws money from an ATM.

One of the strange side effects of modern life is the sheer number of accessories we cart around to confirm that we are who we say we are. Our wallets bulge with drivers’ licenses, Social Security cards, school or company IDs, and credit cards. We have car keys that prove to our automobiles that we’re allowed to drive them, front-door keys that prove to our homes that we’re the rightful occupants. And we need passwords: Of all the irritants of high-tech society, only spam has reproduced at a faster clip.

Passwords have multiplied because of two parallel developments unleashed by the Internet revolution. The whole world is now at our fingertips thanks to the Web, but the world can’t be sure whose fingers are doing the typing. When we greet old friends in person, countless flesh-and-blood traits make us recognizable beyond a shadow of a doubt. So why not use some of those traits to reduce the identity clutter in our lives? So-called biometric forms of identification such as voice recognition and retinal scans have been staples of science fiction for decades, and the former has advanced far enough that it is now possible to ask a computer for directions while driving or to converse with a computer over the phone. But voice-activated computers often have difficulty understanding what someone is saying, let alone making a positive identification of anyone. For the time being, the most promising form of biometrics is still the fingerprint.

DigitalPersona has developed fingerprint hardware and software for home PC users called Password Manager as well as versions designed for businesses. The way it works is simple. You type in the URL for your banking site, for example, and click on the button that says ‘‘see accounts.’’ A pop-up window appears, requesting that you identify yourself. You press your right index finger for a split second on a postage-stamp-size scanner located next to the keyboard, and moments later you’re surfing through that checking account. Then you log on to Discover.com using the same technique. No user IDs, no passwords. Just type, click, and scan. ‘‘It’s one of those technologies that straddle security and convenience,’’ says DigitalPersona’s chief technology officer, Vance Bjorn.

DigitalPersona has already established a foothold south of the border. ‘‘We have a deployment with a Mexican bank called Azteca,’’ Bjorn adds. ‘‘They’ve registered about 4 million people who use our fingerprint technology when they go to make a deposit or use an ATM.” The bank caters to a population of users—migrant workers, for example—who often do not have existing forms of ID.

The DigitalPersona technology uses a small optical scanner to capture a fingerprint image. Before transferring the data to your PC, the scanner must answer a time-sensitive challenge issued from the computer to confirm, as Bjorn puts it, that the ‘‘data is fresh—to ensure someone isn’t replaying the image.’’ The software then stores a description of the fingerprint, focused primarily on a property called minutia points—the locations where fingerprint ridges begin and end. ‘‘Typically, there are 50 to 70 minutia points on a fingerprint,’’ Bjorn says. The challenge of fingerprint recognition is cutting through the static. “There’s a lot of variation in the real world: scars and cuts, different finger placements, dirt on the sensor surface. But the underlying signal of the fingerprint is so strong—because there is so much information unique to it—that even if some of the features are occluded, we can still reconstruct and define the features. If you get in the range of 20 or 30 of the features, that’s enough to make an accurate ID.’’

The ultimate promise of biometrics is a world of fluid movement, unhampered by other props of identity. At work you would log on to your computer with a simple finger scan and check a collection of family photos online with another. Your car switches on after a quick scan of your minutia points, and at the supermarket, you don’t even open your wallet. You simply state your name and scan your finger and tell the checkout clerk that you’d like to use the Visa card associated with your profile.

But if fingerprints are losing their status in the courtroom, why should we trust them at the ATM? The answer is that those two scenarios are fundamentally different. Criminal fingerprints often suffer from what forensic scientists call signal noise, which stems from the print being incomplete. (Most criminals go out of their way to avoid leaving telltale prints for obvious reasons.) Authorities often have to make their match with far less information. The DigitalPersona scanner, on the other hand, produces a much cleaner image of the print. Azteca Bank reports a 97 percent success rate in identifying customers on the first scan. In instances of failure, customers are simply asked to scan their print again.

The other major problem with the forensic science of fingerprints stems from the massive computerized databases that authorities are able to consult, some of which contain more than 10 million individual prints. In an archive that vast, the chance of finding a wrong match greatly increases, particularly if the original print suffers from signal noise. But a system like DigitalPersona’s is not scouring an immense database for potential matches. It’s comparing the fingerprint you’ve supplied with the one it has on file associated with your name. For criminal investigators, if the database contains 10 close calls that resemble the print from the crime scene, that’s a significant complication, because by definition at least 9 of those 10 are false positives. That same risk doesn’t apply in the ATM scenario, because the chance that one of those 10 people—out of, say, 10 million—is stealing your bank card and trying to use it is vanishingly small.

To think of it another way: The world is full of house keys that would fit the lock on your front door, but the likelihood of finding one of those keys is so small that it deters thieves from simply walking up to house doors at random and seeing if their keys work. The same logic applies to fingerprints.

Some people are opposed to biometrics on principle. Consumer fingerprint scanning can seem distinctly Orwellian, the all-seeing eye of Big Brother now embedded in our keyboards. Yet philosophically, DigitalPersona’s fingerprint technology is based on the same fundamental premise as passwords. Both attempt to verify your identity in situations that require confirmation that it’s actually you using the computer. Moreover, statistics suggest that Americans are much more likely to have their lives ruined by identity fraud than by overzealous government surveillance, even in this age of increased security. In 2003 alone, the Federal Trade Commission received 214,905 complaints of identity theft, up from 86,212 in 2001. And because many people don’t file a complaint with the agency, officials say these numbers represent a fraction of total identity fraud cases.

Some estimates suggest that stolen identities cost consumers and businesses more than $50 billion last year. If biometrics were implemented in every major financial transaction, that number might be a fraction of what it is today. It’s unlikely that the government would be able to violate your privacy any more effectively if you replaced all your passwords and other personal identity props with biometric IDs.But doing so might well put identity thieves out of business. In the reality of 2004—and not the fiction of 1984—that may be the most important privacy battle of all.

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