WHEN RUMORS SURFACED early last month that Australian cryptographer Craig Wright would attempt to prove that he created Bitcoin, Gavin Andresen remained skeptical. As the chief scientist of the Bitcoin Foundation, his opinion counts: Andresen is among the earliest programmers for the cryptocurrency, and likely the one who has corresponded more than anyone with Satoshi Nakamoto, Bitcoin’s pseudonymous, long-lost inventor. Today, Andresen fully believes that Wright is Nakamoto. Now he’ll have to convince the rest of the world, because he’s among the only people to have seen what he claims is the best evidence in Wright’s favor. In an interview...