My Quest to Solve Bitcoin’s Great Mystery

One evening in the fall of 2024, my wife and I were sitting in traffic on the Long Island Expressway when, tired of listening to the jazz-funk station I often played on our drives, she switched to a podcast.

It was “Hard Fork,” the New York Times tech show, and the hosts were discussing a new HBO documentary claiming to have unmasked Bitcoin’s pseudonymous inventor, Satoshi Nakamoto.

I was instantly riveted. I had long considered the question of Satoshi’s true identity one of our age’s great enigmas and had poked at it before without success. Two years earlier, I had even spent several months researching a book on the subject. But I soon realized I was out of my depth and reluctantly gave up.

Hearing that someone else might have finally identified the shadowy figure who had revolutionized finance, spawned a $2.4 trillion industry and amassed one of the world’s biggest fortunes in one stroke of staggering genius aroused in me a mixture of admiration and envy. I couldn’t wait to watch the film. As soon as we got home that night, I logged in to the HBO Max app and pressed play.

In the end, I found the conclusion of “Money Electric: The Bitcoin Mystery” unconvincing: HBO singled out a Canadian software developer based on what seemed like very thin evidence. But as I watched what was an otherwise entertaining romp through the world of crypto, one scene caught my attention.

Adam Back, a British cryptographer and leading figure in the Bitcoin movement, sat on a park bench in Riga, Latvia, his shirt untucked under a brown coat. The filmmaker casually rattled off the names of several Satoshi suspects. At the mention of his own name, Mr. Back tensed up, strenuously denied he was Satoshi and asked that the conversation be kept off the record.

Having encountered my share of liars and developed something of an expertise in their tells, Mr. Back’s demeanor — his shifty eyes, his awkward chuckle, the jerky movement of his left hand — struck me as fishy. When the credits rolled up, I replayed the sequence several times on my TV.

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Adam Back, the British cryptographer, in Miami in February.Credit...Amir Hamja for The New York Times

While I pondered Mr. Back’s reaction, another thought occurred to me. An Australian impostor had been sued for falsely claiming he was Satoshi. What if the evidence disclosed in that court case, which had been tried in London a few months earlier, could help me unravel the mystery?

As anyone steeped in Bitcoin lore will tell you, Satoshi was a master at the art of maintaining anonymity on the internet, leaving few, if any, digital footprints behind.

But Satoshi did leave behind a corpus of texts, including a nine-page white paper outlining his invention and his many posts on the Bitcointalk forum, an online message board where users gathered to discuss the digital currency’s software, economics and philosophy. And that corpus, it turned out, had expanded significantly during the impostor’s civil trial when Martti Malmi, a Finnish programmer who collaborated with Satoshi in Bitcoin’s early days, released a trove of hundreds of emails he had exchanged with him. Emails Satoshi sent to other early Bitcoin adopters had surfaced before, but none came close in volume to the Malmi dump. If Satoshi was ever going to be found, I was convinced the key lay somewhere in these texts.

Then again, others must have gone down this road before me. Journalists, academics and internet sleuths had been trying to identify Satoshi for 16 years. During that span, more than 100 names had been put forward, including those of an Irish cryptography student, an unemployed Japanese American engineer, a South African criminal mastermind and the mathematician portrayed in the movie “A Beautiful Mind.”

The most alluring theories had focused on coincidences that aligned with what little was known about Satoshi: a particular code-writing style, a mysterious work history, an expertise in Bitcoin’s key technical concepts, an anti-government worldview. But they had run aground under the weight of an alibi or some other piece of inconsistent or contrary evidence. Each failure had been met with glee by many members of the Bitcoin community. As they liked to point out, only Satoshi could definitively prove his identity by moving some of his coins. Any evidence short of that would be circumstantial.

It seemed foolish to think that I could somehow crack a case that had confounded so many others. But I craved the thrill of a big, challenging story. So I decided to try once more to unmask Bitcoin’s mysterious creator.

I. A Series of Clues

Two Thin Leads

I started by looking for ways to narrow the field.

One thing that jumped out in Satoshi’s emails to Mr. Malmi and in his other writings was that he mixed British spelling and idioms with American expressions. Since many Satoshi suspects are American, some have speculated that he disguised his prose with Britishisms. But I never bought that theory because of a clue Satoshi left us.

In Bitcoin’s first block of transactions, Satoshi embedded text from a newspaper headline: “The Times 03/Jan/2009 Chancellor on brink of second bailout for banks.” The headline in question appeared in The Times of London’s British print edition. This felt like a sign that Satoshi really was British.

Satoshi was also very likely a member of the Cypherpunks, a group of anarchists formed in the early 1990s who wanted to use cryptography, the art of securing communications through code, to free individuals from government surveillance and censorship. The Cypherpunks interacted mostly through something called an internet mailing list. Ancestors of today’s message boards, mailing lists were large group emails in old typewriter font that subscribers received in their inbox. To communicate, respondents replied-all.

It’s hard to picture in the age of Venmo and Apple Pay, but one of the Cypherpunks’ biggest concerns was the digitization of financial transactions. When you hand someone a 20-dollar bill, no one knows where it came from. But when you pay for something with a check or a credit card, banks keep computer records. Cypherpunks worried that governments would use those records to track people’s lives. On their mailing list, they brainstormed about how to create “electronic cash”: digital money that would preserve the anonymity of physical currency. Some even came up with their own electronic cash systems, but none caught on — until Bitcoin.

Besides their shared interest in digital cash, there were other indications Satoshi belonged to the group. He announced his white paper on an offshoot of the Cypherpunks mailing list called the Cryptography list, and he seemed familiar with two of the group’s members.

At its peak in the late 1990s, the Cypherpunks counted some 2,000 followers, so that still left a wide pool of candidates.

Armed with these admittedly thin leads, I pored over Satoshi’s body of writing, especially the emails released by Mr. Malmi, and made a list of words and phrases that stood out to me. It felt like trying to decipher a foreign dialect. More than once, I wondered whether I was engaging in a useless exercise.

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My list eventually grew to more than a hundred words and phrases, taking up several pages in my notebook. Among those that caught my eye: “dang”; “backup,” used as a verb in one word; “human friendly”; “on principle”;“burning the money”; “abandonware”; “hand tuned”; and “partial pre-image.”

One phrase — “a menace to the network” — sounded like a line from a science fiction movie. The rest hinted at a weird combination of upper-class Brit, American redneck, computer geek and cryptographer.

Using the advanced search function on the social media platform X, I did a cursory search to see if any of the dozen or so people most often suspected of being Satoshi used the terms I had highlighted. Not all Satoshi suspects have X accounts, so this wasn’t meant to be scientific. But, just as I had hoped, one person was a match for nearly all of my words and phrases: Mr. Back.

Staring at a long column of check marks I’d jotted in my notebook under his name, I felt a rush of adrenaline. My hunch now seemed at least partially founded. Mr. Back’s use of many of the same terms as Satoshi might not prove anything to a community that had been consumed with this topic for many years, but I doubted it was just chance.

As I took a closer look at Mr. Back, I realized he had several attributes that were consistent with Satoshi. For starters, he was British and he was a Cypherpunk. More important, Mr. Back had invented Hashcash, a statistical puzzle-solving system that Satoshi borrowed for the mining of bitcoins. Satoshi had cited Mr. Back and Hashcash in his white paper.

But Mr. Back had produced emails during the Australian impostor’s trial showing that Satoshi had contacted him in August 2008 before publishing the Bitcoin white paper to check his citation of Mr. Back’s Hashcash paper. Those emails seemed like proof that Mr. Back couldn’t be Satoshi.

As I thought about it, however, I glimpsed a different possibility: Mr. Back could just as well have sent those emails to himself as a cover story.

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‘Down the Cryptography Rabbit Hole’

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With his wire-rimmed glasses, thinning gray hair and goatee, Mr. Back, 55, looks like a disheveled mathematician. Over the past dozen years, he has built a mini empire of Bitcoin-related companies and become one of the community’s most influential members.

Mr. Back has long been among the top Satoshi candidates. But, unlike some other leading suspects, he hasn’t been the subject of close journalistic scrutiny, other than in a 2020 video by an anonymous YouTuber who goes by the handle “Barely Sociable.”

A year ago, I flew to Las Vegas to meet him. He was scheduled to speak at the Bitcoin2025 conference at the Venetian Resort. I wasn’t sure I had the right person, so I wasn’t planning on confronting him yet. I just wanted to get to know him and learn more about his background. If my reporting bore out, I envisioned cornering him with all of my evidence later in a final, dramatic showdown, like a police detective trying to extract a confession from a murder suspect. But for now, I wanted to put him at ease and establish a rapport.

I approached Mr. Back after watching him confidently predict on a panel that Bitcoin, then trading around $108,000, would reach “a million easy” in five to 10 years. (Fittingly, conference organizers had christened the stage he spoke on the “Nakamoto Stage.”) He seemed slightly startled even though I had arranged an interview ahead of time.

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Mr. Back spoke at the Bitcoin2025 conference in Las Vegas last May.Credit...Ronda Churchill/Bloomberg

I told Mr. Back only that I was working on a story about the history of Bitcoin, but he may have suspected what I was really up to because I had already contacted six former colleagues from three companies he had been involved with. If he did, he didn’t show it. He was patient and friendly. It was hard to fathom that this soft-spoken, middle-aged nerd who took no visible security precautions might be one of the world’s richest people. According to Bitcoin lore, Satoshi had mined 1.1 million coins in the digital currency’s early days, a hoard worth $118 billion at the time of the conference.

I found Mr. Back talkative when it came to Bitcoin but more reticent when I shifted the conversation to his early life. I eventually elicited the following from him: He was born in London in 1970. His father was an entrepreneur and his mother was a legal secretary. They moved around a lot, and family members had strong opinions and weren’t shy about voicing them.

Mr. Back said he taught himself how to code on a Timex Sinclair personal computer at age 11 and took interest in cryptography in high school. That became a passion at the University of Exeter when a fellow student turned Mr. Back, who was pursuing a Ph.D. in computer science, onto P.G.P., a free encryption program used by antinuclear activists and human rights groups to shield their files and emails from government surveillance.

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Mr. Back was so taken with the many potential applications of P.G.P., which stands for Pretty Good Privacy, that he said he spent most of his Ph.D. “diving down the cryptography rabbit hole.” He got so sidetracked, he recalled, that he had to cram his thesis into his last six months at the university, comparing himself to a pilot crash-landing a plane.

I’d learned enough by then to know that P.G.P. relies on public-key cryptography.

So does Bitcoin. A Bitcoin user has two keys: a public key, from which an address is derived that acts as a digital safe deposit box; and a private key, which is the secret combination used to unlock that box and spend the coins it contains.

How interesting, I thought, that Mr. Back’s grad-school hobby involved the same cryptographic technique that Satoshi had repurposed.

The topic of Mr. Back’s Ph.D. thesis, he told me, was distributed computer systems: Programs that rely on a web of independent computers known in computer parlance as “nodes” to work together to run their software. This was another technological pillar of Bitcoin.

And Mr. Back’s thesis project focused on C++ — the same programming language Satoshi used to code the first version of the Bitcoin software.

After nearly two hours, Mr. Back politely signaled that he had other commitments that evening, so we cordially parted ways. I told him I would be in touch if I had other questions.