Restrict Access to TOTP Authenticator Key

I have changed the title of this Feature Request topic (was: “Obfuscate TOTP Authenticator Key”) to better distinguish it from the Feature Request Authenticator Key (TOTP) toggle visibility option. The proposals in the current thread express a preference for controlling all access to the TOTP Authentication Key, whereas the other proposal is simply to allow the user to shield TOTP Authentication Keys from the eyes of shoulder-surfers (similar to the way that passwords are obfuscated).