Handprint
A woman gaining access at Daystrom by using her handprint
A handprint was the impression of one's hand used for identification purposes.
In 2368, Data speculated that Berlinghoff Rasmussen's time-pod would open to his handprint, even if he was unconscious. (TNG: "A Matter Of Time")
In 2399, Doctor Agnes Jurati brought Jean-Luc Picard into her office in the Daystrom Institute by using her handprint. (PIC: "Remembrance")