Page242

Retina Scan

A retina scan is a laser scan of the capillaries that feed the retina of the back of the eye. This can seem personally intrusive because the light beam must directly enter the pupil, and the user usually needs to press their eye up to a laser scanner eyecup. The laser scan maps the blood vessels of the retina. Health information of the user can be gained through a retina scan: conditions such as pregnancy and diabetes can be determined, which may raise legitimate privacy issues. Because of the need for close proximity of the scanner in a retina scan, exchange of bodily fluids is possible when using retina scanning as a means of access control.

Exam Warning
Retina scans are rarely used because of health risks and invasion-of-privacy issues. Alternatives should be considered for biometric controls that risk exchange of bodily fluid or raise legitimate privacy concerns.

Iris Scan

An iris scan is a passive biometric control. A camera takes a picture of the iris (the colored portion of the eye) and then compares photos within the authentication database. This also works through contact lenses and glasses. Each person’s two irises are unique, even twins’ irises. Benefits of iris scans include high accuracy, passive scanning (which may be accomplished without the subject’s knowledge), and no exchange of bodily fluids.

Hand Geometry

In hand geometry biometric control, measurements are taken from specific points on the subject’s hand: “The devices use a simple concept of measuring and recording the length, width, thickness, and surface area of an individual’s hand while guided on a plate” [7]. Hand geometry devices are fairly simple, and can store information in as little as 9 bytes.