Except in other contexts, the use of the public and private keys is reversed. I use my private key to generate signatures: does it aid understanding to tell someone to use my "lock" to verify such signatures?
Just tell the user he can't sign things without a profile, and make keys with each profile.
good point
but maybe this is a different thing conceptually
i think i would call that a stamp or a seal
..sort of like a wax imprint of a key