claustrarius

ἐξ ὀνύχων λέοντα τεκμαίρεσθαι → judge by the claws, judge by a slight but characteristic mark, small traits give the clue to the character of a person, deduce something from a small indication, identify a lion from its claws

Latin > English (Lewis & Short)

claustrārĭus: a, um claustra,
I pertaining to locks: artifex, a locksmith, Lampr. Elag. 12.