Matching templates and preventing spoofing
Once the encoded template is created, the system will either identify or authenticate, according to the design.
The template is compared against a record in search of a match. As with any biometric, the match will never be 100%. Matching occurs as a result of whether or not the threshold is acceptable.
One way to evaluate whether a sample matches a template is by calculating the Hamming distance. The Hamming distance is the result of comparing two binary values, as we’ll see next.
Calculating the Hamming distance
The Hamming distance is a comparison of two binary values. To calculate the Hamming distance, we use an exclusive OR (XOR) operation on both values. When complete, count the number of bits that are equal to 1, and that will be the Hamming distance.
Important note
An XOR operation is a logical operation that compares two values. In an XOR operation, if A =1 and B =1 but not both, the output is 1.
For example...
