Using OneName/Namecoin blockchain as global nickname registry

@ryanshea How does a user authenticate ownership of the name? Does the namecoin protocol allow you to sign a message demonstrating ownership of a particular key/name? (I guess this would be like using a BitCoin wallet’s private key to sign a message demonstrating ownership of it, but I don’t know if that’s how it works.)

Is the passphrase used by onename.io using some kind of standard way of deriving a key, such that the same passphrase could also be used to modify the record by other namecoin/onename clients? (i.e. does onename.io create any sort of lock-in?)

I find the idea attractive, I just want to make sure I understand the way it is decentralized.