Biometric Systems Provide Security by Reading Physical Signs

From Associated Press

Biometric identification mixes cutting-edge technology with human body parts to confirm identity for financial transactions, security and other purposes for business and government.

The different systems rely on unique physical characteristics recorded and enrolled in a database for later verification. None appears perfect for all uses, and some are still too expensive or not ready for widespread commercial use.

A sampling:

* Retina scanning: A lens apparatus illuminates the eye and scans reflections of the vascular structure of the retina, the membrane behind the eyeball that receives images. Hundreds of data points are recorded and stored as a digital code. EyeDentify Inc. of Baton Rouge, La., has patents controlling the technology, which it says has never falsely accepted anyone in 10 years. The company has sold systems to banks, jails, the Illinois state welfare program, foreign governments and U.S. agencies from NASA to the CIA.


Drawbacks: While generally stable throughout life, vascular patterns can change with injury and a few illnesses; the face must be within a few inches of the scanner; eyeglasses must be removed.

* Iris scanning: A camera photographs one iris, then converts it to a digital code. When an enrolled subject is being verified, the camera checks for pupil movement to ensure it is not viewing a photograph.

Drawbacks: Camera may have difficulty reading very dark irises; very dark or reflective sunglasses must be removed; dirty eyeglasses can cause false rejection.

* Face recognition: Part of the face is photographed, then the three-dimensional image is converted to digital code.


Drawbacks: Face shapes change with aging and weight fluctuation; some scanners can be fooled by people who look alike; a photo can pass as a person on two-dimensional scanners, while three-dimensional ones require huge digital codes.

* Fingerprints: Optical scanning of a fingertip pressed against a glass plate has replaced ink pads.

Drawbacks: Dirt and other substances on skin can smear the plate; injury can scar prints and heavy labor can wear them smooth; database searches are too slow for instant verification.

* Handprints: An optical reader scans the geometry of the whole hand, or the index and middle fingers.


Drawbacks: Injury and major weight fluctuations can alter the hand; hand and finger shapes are not as unique as fingerprints.

* Voiceprints: The unique frequencies of a person’s voice are recorded and converted to digital code.

Drawbacks: Illness and allergies can alter voices; the subject must perform by responding to the system’s prompt, although that prevents tricking it with a tape recording.

* Signature verification: An online writing device compares the signature to one in a database.


Drawbacks: Devices have fairly high error rates and are susceptible to forgery; signatures deviate significantly over life, and sometimes when the subject is ill or impaired.