Twelve (12). However, Ninety-Six (96) Personal faces are necessary for security. FaceGuard’s Guide to Gathering Personal Faces lists hundreds of hints.
Critically, the brain is extraordinarily adept at recognizing faces. Everyday life confirms humans are easily capable of differentiating thousands of faces. Emotional connection virtually assures immediate recall even when the viewer hasn’t seen a face in decades. As a species, we enjoy photo albums, yearbooks, and now digital displays. Similarly, a magical aspect of FaceGuard is each access is a memory. Users report they enjoy using FaceGuard whereas they hated passwords.