mask.of.sanity writes "An Australian high school has installed 'secure' fingerprint scanners for roll call for senior students, which savvy kids may be able to circumvent with sweets from their lunch box. The system replaces the school's traditional sign-in system with biometric readers that require senior students to have their fingerprints read to verify attendance.
The school principal says the system is better than swipe cards because it stops truant kids getting their mates to sign-in for them. But using the Gummi Bear attack, students can make replicas of their own fingerprints from gelatin, the ingredient in Gummi Bears, to forge a replica finger. The attack worked against a bunch of scanners that detect electrical charges within the human body, since gelatin has virtually the same capacitance as a finger's skin."
This process can check if this value is zero, and if it is, it does
-- Forbes Burkowski, CS 454, University of Washington