What I'm trying to achieve, is to have a very simple way of authenticating yourself with one Bitcoin address from your wallet.
For most of the people using Bitcoin, their wallet is on their phone.
The UX is clear and simple :
1. click on "connect with Bitcoin" (the audience is normal people)
3. accept the authentication request (same style than OpenID or Facebook connect)
4. user is autologged and identified by the chosen Bitcoin public address
It makes sense only if major wallets are supporting the protocol. If you need to install a plugin or download a third party software, no one will do it.
I see only benefits for the entire ecosystem, and if I'm working on such a proposition it is because I really need this feature.
Of course, it can be done without a BIP, I just need to convince wallet developpers one by one to implement the feature.
But I thought it was much better to start the "official" way, so all wallet could easily find and implement the same authentication mechanism.
> Bitcoin and website authentication are unrelated problems
I respectfully disagree. Many services require your Bitcoin address, and to do that they artificially request an email/password to store it.
This is not about authentication as an identity (as "I'm Eric Larcheveque"), but as in "I'm proving to you that I control this address".
Without such a standard protocol, you could never envision a pure Bitcoin physical locker rental, or booking an hotel room via Bitcoin and opening the door through the paying address.
Eric