For clarity: Despite anything you may have heard, the biometric scanner does not take your fingerprint. It measures aspects of the shape and size of your finger and creates a score which is henceforth associated with the ticket.
Two people with different size and shape of finger might very well still have the same score as a result of the algorithm used. The odds are that if you steal/find someone else's ticket, your score and theirs won't match and you won't be able to use the ticket. But it's not impossible.
Correct.
For those that want to know what it is, in programming it is called a one way hash.
The machine reads certain parameters of your finger, it then hashes a value based on those measurements and puts that value in a table.
When you enter again it checks to see if your finger parameters, when passed though the hashing function again match what is in the hash table.
It is impossible to take the value in the hash table and go the other direction and determine ANYTHING about your finger scan
Lets say it takes 5 measurements, that can have a value of 1 to 5
Your finger comes up 1, 4, 4, 2, 5. Lets say the hashing function is a simple sum, so your hash value is 1+4+4+2+5 = 16
If someone for some reason was to get your hash value, they have no idea if you finger scans as 1, 4, 4, 2, 5 or 5, 1, 1, 4, 5 or 2, 2, 2, 5, 5 or any of dozens of possible combinations.
It's not sinister, and it stores nothing of any use to anyone except the ticket turnstile.
-dave
