Request for Ethereum address verification

I'm looking to have a group chat for pseudonymous individuals who can prove that they own a specific Ethereum private key.

There's ways to do this currently but it would be much nicer to have an integrated solution. Effectively how I see this working is that keybase would ask the user for their ethereum public key and then would require them to sign a message with their Ethereum private key that says something like: "My keybase username is foo with id bar".

The issue names no files, tests, or entry points, so begin by locating Keybase's group-chat identity and proof-of-ownership flows. Define the Ethereum public-key registration and signed-message verification requirements before implementation. Done would mean an integrated flow that verifies ownership of the specified key and makes that identity available in pseudonymous group chat.

Written by the indexing model from the issue text.