For the rest of the world, it all started in the Fall of 2008. There was a mailing list that only the most geeky geeks listened to, and one dude nobody had ever heard of before posted a whitepaper. People started working with him because he seemed to have a great idea. Then things took off. Then they really took off. Then, one day, the man didn't say good-bye, but handed over the keys to the idea to a bunch of friends. And disappeared. And then, a little over three years later, he sends a message from the cyber-grave. Only to tell us he's not someone.
When Bitcoin was young, there were services that gave Bitcoins away so people could play with them. You logged onto one of the sites and got 5 Bitcoin (or BTC for short) for free, just like that. You could go back as many times as you wanted. Today, those 5 BTC are enough to buy you a car. Depending on the day it's a beater or a beemer.
The man that published the whitepaper and then disappeared has a name, Satoshi Nakamoto. Nobody knows if that's the man's real name. Nobody, in fact, knows if Satoshi Nakamoto is a single person, or a woman. He claims to be Japanese, claims to have been born and to live in Japan, but we have good reasons to believe neither is the case. He says he was born on April 5th, 1975, but nobody can verify that.
And yet, Satoshi Nakamoto has given us a technology that has the potential of changing the world. He's like a faceless prophet that leads his people to a better land and vanishes in self-exile once we get there, following the commandments of a God we do not understand. And because he vanished without a trace, because he didn't leave a whole lot of traces to begin with, and because Bitcoin has become so huge, everyone is asking the same question: Who is Satoshi Nakamoto?
Nobody seems to have met Satoshi in person. He existed only, as far as we know, virtually. Because of that, the vast majority of his interaction is recorded publicly. There is the whitepaper mentioned and the site it lived on. There are the messages exchanged with the curious and with fans. Finally, the source code of the client he worked on, the thing people could run on their computers to create and trade Bitcoin.
There are numerous sites that collect all that information. One I found particularly useful is the oddly named satoshi.nakamotoinstitute.org. There you will find everything I mentioned before, and a few more tidbits.
Since the only record of Satoshi we have is written, it's important to look at the language he uses and how he uses it.
Satoshi writes in English exclusively. He seems not to speak any language other than English proficiently, especially not Japanese. We know that because when the Bitcoin client was translated (localized), he did not contribute a Japanese translation, despite desperately needing any language translation to test the ability of the client to show languages other than English.
The first translation languages were Italian, Dutch, and German. Satoshi may have been the author of one of those, contributing anonymously not to reveal his actual country of origin.
Satoshi's English is almost flawless. He makes virtually no spelling mistakes, ever - including in forum posts that come in rapid-fire mode. His language is very deliberate and easy to read. The few exceptions indicate there was no editing going on (that is, several people contributing to the text in successive edits). People have noted that there are both American and British peculiarities in the text. For instance, he spells "neighbours" consistently the British way, while "color" is always the American way. He says "analyse" the British way, but throws a "Yeah" into the mix like a good old cowboy. Note that the British and American spellings and idioms are mixed together in the same message.
The only idiomatic oddity I could find is that instead of saying "almost always," he uses "mostly always." He uses the construct twice, indicating it wasn't just a slip but an idiosyncrasy that could potentially tie him to a particular set of geographical areas or social circles.
The only misspelling I could find was a single "uncompressible" instead of "incompressible." Because the word "uncompressed" precedes it almost immediately and because the letters U and I are next to each other on the keyboard, it's hard to tell if this was just a typo.
Satoshi is, with one exception, unfailingly polite and helpful. This is particularly surprising, because there was frequent stress in the early days and frequently repeated questions. Satoshi would reply with a preternatural politeness and joviality.
When Satoshi didn't know something, he had two approaches to deal with it. One one side, he might sneak off in the background and become a relative expert in the field by the time he replied to the question, or he would admit he didn't know and ask for help.
Satoshi was quite proud of his accomplishment and relished the compliments he received from luminaries in the security field.
Satoshi's Programming Skills
Interestingly for someone who published a whitepaper, Satoshi released software that ran the protocol outlined shortly after receiving attention. Anyone interested could download the software and run it on their computers, and after a short while (less than a month) several people did. This was in sharp contrast with proposals for cryptocurrencies from others, that saw an implementation much later.
For someone interested in cybersecurity in 2008/2009, Satoshi had a peculiar set of skills. His client ran only on Windows and used the open-source cross-platform library wxWidgets. It was written in C++, the standard programming language for serious development on Windows.
Soon after the initial release, it became clear that the cybercommunity wanted a Linux client. This is when Satoshi revealed he didn't know much (or anything at all about Linux). He would run Linux on his computer and slowly become more and more proficient, but he was often frustrated by problems on Linux systems, in particular version incompatibilities.
Satoshi asked for someone to write a Python and Java client, clearly tasks that were beyond him. The web interface (JSON-RPC) was written by someone else.
In summary, it appears that Satoshi's programming skills and knowledge of computers were relatively shallow. At the same time, he frequently uses jargon typical of Computer Science majors (like correctly identifying that an algorithm is n log n), indicating that he has schooling in the matter.
Satoshi's Security Skills
The design of the protocol and client seem to have involved a whole lot of thinking and figuring, as Satoshi recounts himself. He is proud of finding out that he has thought through all the scenarios for attack that other cybersecurity people throw at him.
The technology used in the client is solid, proven, but not particularly sophisticated. Satoshi uses hashing and digital signing, but refuses to use encryption because of the size overhead it brings. He might either have been conservative and safety-minded, or not very deep.
The one item that is highly unusual for a cybersecurity person is the fact the algorithms for hashing and signing cannot be altered. A cybersecurity person is very conscious of the fact that algorithms fail after a while, because she or he has to scan the horizon for possible known attacks. Hardcoding an algorithm is both unnecessary and stupid. In fact, at some point Satoshi has to explain what he plans to do if the algorithms he picked turn weak, and his response requires either throwing out blocks manually, or updating all clients in the world and hoping the new software with the new algorithm runs on the majority of computers.
Satoshi's Economic Expertise
The use of technical economic terminology unmistakably indicates that Satoshi had some form of exposure to the world of finance, possibly a financial institution (particularly a bank). I think the most uncommon word I could find in his writing is "seigniorage," a word I wouldn't imagine is part of the vocabulary of a great many software developers - although it is certainly important in the development of a currency.
There is one odd wrinkle in his economic thinking that indicates he was in contact with the world of finance but not immersed in it. Bitcoin is obviously very concerned with security. It protects your money with private keys that you have to keep safe. If a private key is lost, the money indexed by it is also lost. That means that if you ran your client on your computer and stored Bitcoin on there, but the computer crashed, that money was gone for good, never to be retrieved again.
Someone pointed that out to Satoshi, using the term "natural deflation." Satoshi liked that and used it henceforth, indicating that the only downside of this natural deflation was that everybody else's Bitcoin was worth a little more.
That is certainly true. The problem is that there is only a certain finite amount of Bitcoin to ever be created. What that means is that this natural deflation will eventually eat up the entire supply of Bitcoin. There is nothing cute about natural deflation, as it spells the natural end of Bitcoin. I find it very surprising that Satoshi didn't see that.
Obviously, anonymity was very important to Satoshi-the-person. It became an important feature of Bitcoin, as well, and one of its major selling points in the beginning. In fact, the first big increase in bitcoin value came when users of the website Silk Road started using it. Bitcoin was promised to be untraceable, so that users could order and pay for illegal wares anonymously.
This was of course before 2013, when the Snowden revelations proved that this anonymity was fallacious. In 2009, it still seemed like a good protocol could hide everything from the world.
That anonymity is so important to Bitcoin is also due to the fact that everyone can see every transaction ever made in Bitcoin at all times. There is no hiding of the flow of money, and that's because of the very nature of Bitcoin's approach.
Also, the protocols required to achieve anonymity were already developed before Satoshi started development.
The most important innovation of Bitcoin is its peer-to-peer approach. Every other cybercurrency proposal required some form of third party (a "bank") to function as arbiter of the flows of money. For party A to pay party B, party A would first pay the bank, who then gave money to B. This was mostly so that A couldn't pay both B and a third party, say C, the same amount. Since cybercurrency is not physical, making copies of it is trivial.
The thought process that Satoshi followed seems to have started with the peer-to-peer approach. The technical solution he came up with was the way to make financial transactions possible without a bank. Many of the technical questions he fielded in the forum were answered with the importance to make the system work without this bank.
Interestingly, Satoshi was a member of the P2P Foundation, an advocacy group for the peer-to-peer approach headquartered in Amsterdam. Satoshi's last message, in fact, was sent on their site, in the form of a new comment to the original announcement of the Bitcoin whitepaper.
An analysis of the timing of messages indicates that Satoshi was mostly sleeping during what would have been night on the United States East Coast. He was relatively regular and, given typical programmer propensities for late waking, it is unlikely he would have been much to the West of the Coast. On the other hand, because of the break posed by the Atlantic, it's unlikely he would have lived on the opposite coast of that ocean.
An interesting gap occurs in his replies to messages at the end of 2009. His last message is from 12/18 of that year, the next one is from 1/5/2010. This is important because that last day is the last Friday before Christmas, while the next one is the first Tuesday after New Year's. That indicates that Satoshi was gone for the holidays and had no access to the Internet or a computer.
We have a few hints as to the equipment available to Satoshi. He seems to have worked on a Windows XP laptop, on which he ran Linux in a virtual machine and in dual-boot. It must have been a newer model, since he couldn't test the compliance of the older Pentium 3 processor. An odd peculiarity is that the laptop didn't switch to text mode when pressing Ctrl-Alt-F1. The screen instead went haywire.
It is almost certain that Satoshi is not the person he describes himself as. He wasn't living in Japan at the time of Bitcoin's birth and he didn't speak Japanese. The references quoted in the whitepaper, on the other hand, indicate he would have read them as a college student for a thesis/homework on document chaining if he had indeed been born around the time he says.
The mix of British and American spellings combined with the likely presence on the East Coast of the United States during the birth of Bitcoin implies he learned British English first. This could be because he was from a Commonwealth country, as often stated, or because he learned British English, as many school children do in the world. That is particularly true for the European continent.
Satoshi most likely was a single person and not a group. This is due to the consistent language used throughout the two years of his online existence, as well as the unlikely possibility, a collective could be so coordinated and cohesive even after years. The nature of Bitcoin, which reuses building blocks already readily available to combine them into a new idea with just minor (if brilliant) tweaks, also implies there was no directorate of collaborators.
Satoshi was not a professional in the economic or cybersecurity fields, but was very proficient in computer sciences. For a software developer, on the other hand, he had a very limited toolset to work with.
Many strands in Satoshi's world point back to Europe, without any conclusive proof. Satoshi's first collaborator is a Finn. The P2P Foundation mentioned earlier is headquartered in Amsterdam. The three first translations of the Bitcoin software were Italian, Dutch, and German. The message embedded in the first (Genesis) block of bitcoin is a reference to the print version of the London Times.
The Satoshi that emerges from this profile is a European programmer born in the mid-70s. He went to college and later emigrated to the East Coast of the United States, where he possibly worked for a financial institution. He survived the financial collapse relatively unscathed and created revolutionary technology for the benefit of humanity, or for play, or for recognition. Certainly not for profit.
This profile, sadly, also hints at a very possible reason why Satoshi had to be anonymous and had to disappear. As a foreigner working in America, he may have not realized that most employment contracts in high tech include clauses that reassign all intellectual property created by an employee to the company (s)he's working for. It is beyond doubt that Satoshi worked on Bitcoin during working hours - as source code checkins and forum posts prove.
The reason Satoshi may have had to disappear may have been simply the realization that revealing his identity might have destroyed his project, by making it the property of the financial institution he was working for.