Meetings with Satoshi
It was in a conference room above a coffee shop a fifteen minute walk from BBC Broadcasting House that we first met the man who says he is Bitcoin creator Satoshi Nakamoto.
As we walked in, three or four people were waiting around a table - but which one, I wondered, was the father of Bitcoin?
Then I realised that one man was staring intensely at a very chunky laptop - this was Dr Craig Wright. He carried on working, apparently unaware that we had entered the room.
Once we had been introduced he gradually warmed up - especially when it came to performing the demonstration that showed that he did have access to the cryptographic keys used by Satoshi when he made the first Bitcoin transaction in 2009.
We had arrived wondering just how convincing a case would be made that the almost mythical creator of Bitcoin was at last stepping out of the shadows. What we saw seemed impressive - though it would need a far higher level of expertise than we possess to be certain.
But Jon Matonis, a senior figure in the Bitcoin world, was in the room watching, having had his own demonstration some time before. And the news that Gavin Andresen, chief scientist at the Bitcoin Foundation, was also convinced provided more reassurance. Now Craig Wright has published his evidence on his blog, it will be examined in minute detail for any chink in his case.
But put aside the question of whether you believe him or not - and he told me he didn't care either way - there were still plenty of questions we wanted to put to the fascinating, if somewhat prickly Dr Wright. Why keep his secret so long? Why come out now? What about that run-in with the Australian tax authorities? And is he fabulously rich, with a huge stock of Bitcoin?
At our first meeting - without a television camera - we roamed freely over all sorts of territory. We learned that he ran a substantial business in London, employing quite a few people here in what seemed to be some kind of Bitcoin trading and consultancy operation.
We challenged him about that tax investigation - he conceded that there was what he called an "audit" underway in Australia but insisted that this was mainly due to the tax authorities there not really understanding Bitcoin. We asked where the pseudonym had come from - he mentioned a 17th century libertarian philosopher called Nakamoto but said he'd keep the Satoshi bit to himself.
He talked of the French writer and philosopher Jean-Paul Sartre, whose statement refusing the Nobel Prize is used in the Satoshi-signed file given as evidence in the blog published today. His politics were very far from the "lefty" Sartre, he explained, but like him he did not want his identity to be defined by one thing - he refused to be Craig "Satoshi" just as Sartre did not want to be Jean-Paul Nobel.
What he wouldn't say is how many Bitcoins he has - "that would be telling" - though he indicated that he would not be spending any of them in a hurry. He told us that he had a "nice big house and a nice fast car" in London, went on holidays to Paris, and didn't feel the need to acquire vast riches.
The second time we met, to film a television interview, the mood changed. It was immediately clear that he hated the whole process, refusing to move from behind his laptop to a more spacious room where the shot would have been much better.
At first, he insisted that he would give an answer to just one question - why he had decided to go public after all these years. Once we started filming he opened up a little, but mainly because he wanted to express his anger at, as he sees it, being forced into the public eye.
"I don't want money, I don't want fame, I don't want adoration, I just want to be left alone," he said with some venom. He accused journalists of threatening to make up stories about him if he did not cooperate and said lies had been told that would affect his family and his staff.
It seems his main grievance surrounds the stories that spread last December when he was first identified as a potential Satoshi, then dismissed by some as a hoaxer. At that time, questions were asked about his academic and business career, and there were some who said he just did not have the intellectual capacity to be the man behind Bitcoin.
Throughout the demonstrations he showed us he kept on stressing the complexity of the process - "obviously everyone said I have no idea about this stuff so I'm going to do it in the most convoluted way possible". We were then supplied with a series of documents providing evidence that Dr Craig Stephen Wright was a Master of Statistics, IT Management, and Law, and a long list of peer-reviewed articles.
Now he says he intends to continue his research into improving the technology behind Bitcoin, and plans to publish several papers over the coming months. With the community around the currency in some turmoil right now over how it develops, you might think that Craig Wright could provide some leadership.
After all, he could be said to be to Bitcoin what Tim Berners-Lee is to the web.
But he bridled at my suggestion that he could be a figurehead for the currency, making clear that this was the first and last television interview he would do. Having emerged from the shadows, Craig Satoshi Wright now wants to return to them as quickly as possible.