https://telegram.org/blog/passport, for example.
> People would submit their national ID number or full name, and get back a crypto key, and there could only be one key per national ID?
Usually, with a KYC service, people submit photos of their identity documents, and sometimes also video of themselves vouching for the document (as if you were having an asynchronous conversation with a notary public.)
Later, if someone else comes along and tries to register the same credentials and also presents the same level of evidence, you get a human arbitrator involved and ask each party to present more evidence, e.g. another primary identity document, or an actually-notarized letter of identity claim, etc. The same sort of things you give the police in an identity-theft case.
... Like Reddit and HN, with improvements: https://www.talkyard.io/-32/how-hacker-news-can-be-improved-... (sorry for promoting my own thing ... I don't know any other seemingly okay open source Reddit alternative though)
Interesting, that there's "lots of" discussion software, but not yet any single login system like the one you describe. (?)
> need a real physical ID to get [a crypto key]
How can that work :-) People would submit their national ID number or full name, and get back a crypto key, and there could only be one key per national ID? How can one know that the one that submits the ID number, is the person him/herself? Maybe by looking up the person in the country's telephone directory, and sending a snail mail or making a phone call to verify?
What if there was an open-source verified-real-life-identity + crypto key login system, which could be connected to all different discussion software with a Single Sign-On API?