Cryptography Reference
In-Depth Information
of vendors grows from one year to the next. As you can see in Figure 6.11,
the wealth of ideas seems to be unlimited.
•
Fingerprint:
A fingerprint is taken as the finger is placed on, or moved past,
a sensor. Fingerprint sensors can be found in keyboards, mice, and special
USB sticks.
utimaco Software AG
even developed a crypto-smartcard with a
built-in fingerprint sensor.
Older systems could be fooled by using fingerprints printed on scotch tape.
In modern systems, expensive sensors additionally check the temperature and
some even the pulse beat and the pigmentation of the finger cup on the print.
Some people might be cruel enough to cut somebody's finger off to use it for
identification. Modern impostors are more humane (and still very successful)
using simpler means, as the German Chaos Computer Club demonstrated: you
need a digital camera, a simple image editing tool, a printer, and some liq-
uid plaster to create a thin skin with the desired (stolen) fingerprint pasted to
your finger. The funny thing is that this system passes all live tests (for finger
authenticity). And with some extra talent, it even works under observation.
You can find the article and the link in
txt/biometric/fingerprt gelatine.txt
on
the Web site.
Dirty or injured fingers cause problems. Some systems compensate for injuries
by accepting different fingertips. Also, the sensors themselves can be dirty.
In addition, about 2 % to 5 % of all people don't leave usable fingerprints
(e.g., carpenters or masons). Those who use fingerprints as a replacement
rather than an addition haven't understood the concept of biometrics. It is a
system mistakenly believed to be highly reliable, especially since it is used
as legal evidence. But fingerprints in criminal investigations are taken dif-
ferently (by rolling all ten fingers on a sort of ink pad), and the problem of
liveness-checks doesn't exist in this field.
Excessive use of fingerprint sensors and careless data protection can even
cause fingerprints to be worthless as legal evidence, because it is too easy to
forge them and, above all, they are not secret anymore.
•
Facial recognition:
Outstanding points or the three-dimensional shape of a
face are detected and measured. If you select points the distance of which does
not change, then the system would recognize you even after a night's carous-
ing. Problems can be caused by eyeglasses, beards, injuries, anti-wrinkle
creams, aging, and photos held in front of the camera in older systems.
Figure 6.11:
Examples of biometric systems.
