While not an answer to your question, I'd recommend that when you write the code you incorporate some double-check type of algorithm into the program. As an end-user of a finger print scanning security system I am continually frustrated. The security officer that installed the system sums my troubles up by saying "You have a problematic fingerprint". Nine times out of ten the program will not match my fingerprint and refuses me entry to our server room. Eventually, if I keep trying it will recognize my print as being "authorized" and the door will finally open.

If you find some perlish solution to this task, I hope you'll be able to find a better way to do it.