What is a symbol for secrecy?

Answer 1

It's a rose, as in the latin term, Sub Rosa, which means "under the rose." It is an old custom that at any meeting in which secrecy was required a rose is hung over the door. Meaning that anything said inside was never to be talked about.

Answer 2

A symbol commonly associated with secrecy is a lock or a keyhole. It represents something that is hidden or confidential, requiring access or permission to uncover.