Those two features were present for a long in Bitcoin Core, but has been scarcely used over the years. However, this is going to change with [AOPP](https://gitlab.com/aopp/address-ownership-proof-protocol/-/blob/master/wallet_guide.md) who directly link at [this code](https://github.com/bitcoin/bitcoin/blob/13d27b452d4b60010c54d4f80757dea9805076be/src/util/message.cpp) in the protocol's implementation. I think it is time for this signature protocol to retire before it is misused.
