Biometric Authentication Attacks (2D)

Biometric matchers never compare templates exactly — they score similarity on a 0-to-1 scale and accept anything above a threshold, which means genuine users and forged samples (fake fingerprints, printed or masked faces, replayed scans) both land somewhere on the same axis. This 2D companion draws that scale directly: a live threshold line splits an accept band from a reject band, and every presentation — circle for a genuine user, diamond for a spoof attempt — travels across the stage toward it. Raise the threshold and spoofs get turned back, but real users start bouncing off it too; raise spoof sophistication and the two score bands drift together; toggle liveness detection (PAD) to see an independent check catch attacks the score alone would have passed. The same FAR/FRR formulas as the 3D version drive the outcome — this view just lays the score axis flat so the threshold trade-off is easier to read at a glance.