Now that we know what
constitutes the iris biometric, and how it can be
captured, we need to know how the algorithm works.
Once an iris is
captured, it is then transformed into a template that is 2,048 bits in length.
To evaluate a live template to the orientation template, a simple restricted OR
(XOR) operation is done on the two values. Their equivalent mask bit vectors
are used in an AND operation to verify that there were no artifacts affecting
the assessment. The norms of the resulting XOR and operations are used to calculate
a Hamming Distance. The Hamming
Distance is a establish of difference between the two iris templates. This
distance is then used to conclude whether there is a match or not. Since there
are many degrees of independence in the iris code, a relatively large Hamming
Distance can be used to still assurance a near-zero FAR. This simplicity of the
algorithm allows for very fast matching in the range of 100,000 per second on a
300MHz machine.
How Can This Biometric Be Spoofed?
The iris is an
extremely difficult trait to spoof, yet there have been attempts at spoofing.
There is little doubt that others will try and, given enough time, money, and
energy, they may be successful. Attacks on the iris biometric fall into the following categories:
·
Attacking the physical iris
·
Using artifacts
·
offensive the communications
·
Compromising the pattern
·
offensive the fallback system
Iris biometrics appears to offer the Holy Grail of biometrics.
Iris biometrics is quick, robust, and fast to measure
up to, and refuse to accept spoofing better than any other trait so, this
should be the ideal biometric for network security. From a pure technological position, it is the clear winner,
hands down. The last difficulty to be answered is: Why has the iris biometric not overtaken every other biometric and been widely deployed? The reasons
are quite simple:
1.
Hardware cost— particular cameras are still necessary.
These cameras need to have their own exclusive light source. As such, there are
only certain economies of scale that can be leveraged to decrease the cost of
the hardware. Sustained research in this area will yield lower-cost products.
2.
User awareness— Even though it is quite clear that
the infrared light being used is completely safe, the mere thought of incredible
being shined into the eye is disturbing to the user.
3.
Placement— to get the iris in the proper
position takes a fair amount of management. Therefore, some users will never be
able to use the product, and others will require longer times to become fully familiar
to its use. Some cameras use eye acknowledgment techniques to try to auto-pan
and focus the camera. These solutions, while better, do increase the cost of
the camera and may still require some user management.
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