OMG, people! "Public" in "public key" doesn't mean that you should share it with the whole world, it's just because it's an antonym of "private key", meaning th

OMG, people! "Public" in "public key" doesn't mean that you should share it with the whole world, it's just because it's an antonym of "private key", meaning that the other party you want to communicate with doesn't need to have a pre-shared secret key with you. Other party may be the whole world, but may be not. How public key is used is up to a protocol and threat model: it may as well be secret, and yes, in some protocols and threat models security can depend on public key being secret, and it's not wrong, and not "security by obscurity".