No proof publically available yet.
Indeed, there are many much easier ways for him to prove it but he's chosen not to do any of them.
From what I've read he's shown he has the keys used in the first bitcoin transaction. That's pretty decent evidence.
What are the easier ways to prove it?
@hippy started
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Indeed, there are many much easier ways for him to prove it but he's chosen not to do any of them.