Against the Rules On Background: Bad Actors on the Blockchain

Michael Lewis

Hello, Against the Rules listeners, it's your long-lost host, Michael Lewis. I miss you guys and it's going to be a little while before I come back, and I want to explain what we're doing. I'm in the middle of a book. It's about FTX, the cryptocurrency exchange that has collapsed in the last few months in dramatic fashion. It's taking all my time, but there's this thing I do with books. I do a lot of interviewing around the book, stuff that's never going to be in print just to educate myself around the boundaries of my subject, and talk to a lot of interesting people for this.

All the stuff winds up on the cutting room floor, except in this case. What we're going to do, is basically call up a bunch of experts and talk to them about what they know. You'll be getting the same kind of education I get before I put words on paper. I hope you find these people as interesting as I do, and you can hold your breath until Against the Rules is back out towards the end of the year. Welcome to On Background from Against the Rules. I'm Michael Lewis.

The cryptocurrency movement arose on the back end of the 2008 financial crisis, in response to the crisis, in response to the perceived injustices of the global financial system. The transparency, decentralization, and global nature of the blockchain are supposed to have made it safer for cryptocurrency traders and investors, but it also makes it easier for bad actors to hide illicit activity. How much illicit activity is there? The cryptocurrency analysis firm, Chainalysis, estimated that there were $14 billion worth of shady dealings in 2021 alone.

Tracking crypto crimes could be a nightmare, but there is a way, and I need to understand the nitty-gritty of how it's done. I called up Andy Greenberg, who's the senior cybersecurity writer for Wired, and author of the new book, Tracers in the Dark: The Global Hunt for the Crime Lords of Cryptocurrency. I love the book. It's a series of stories, case studies of cracking crypto crimes. It'd make a wonderful episodic television drama and it explores the growth of illicit commerce with crypto.

Andy also follows some US law enforcement agents, who tracked illegal transactions around the world, to figure out how they did it. It reads like a thriller. I mentioned that I've gotten very interested in the FTX story and I'm curious, do you share an interest? Have you been following it?

Andy Greenberg

Yeah. I'm interested in it, but largely from the sidelines because it's not like a crypto crime story. It's not my kind of story exactly, except for this one element of it. Just after FTX declared bankruptcy, something like half a billion dollars worth of cryptocurrency was pulled out of its accounts by an unknown person.

That appears to have been a much more traditional, straight-up theft by we don't know who. An insider perhaps, Sam Bankman-Fried himself maybe, or was it hackers who just seized on the chaos of this meltdown to try to pull off a big heist?

Michael Lewis

It's precisely the kind of heist that your book suggests is a fool's errand because that Bitcoin, that crypto's going to be traced and followed wherever it goes.

Andy Greenberg

Right. As soon as this happened, I started calling up my tracer friends and sources, I should say. They were following this money in real time, as it was being stolen basically. This is the crazy thing about cryptocurrency, which is that even if you can steal it, everybody can watch your getaway car make every turn through the city map.

They're just waiting for you to try to get out and cash that stolen money in somewhere at a bank or whatever. I don't know what the end of this metaphor is, but they can follow you as you do it. It's going to be extremely hard for whoever took that money to liquidate it, to use it in any way without being identified. Then we'll find out if it was an insider or a thief.

Michael Lewis

When you first got interested in crypto, in Bitcoin, and a completely innocent person asked you to explain to them what crypto was, what was your go-to explanation?

Andy Greenberg

I think I would've described it as just digital cash, and in the sense that you can keep it under your mattress, you can keep it on your computer, and nobody else has to know about that.

You can spend this digital cash, this cryptocurrency, in a dark alleyway without anybody, including the person you're sending it to, knowing who you are.

Michael Lewis

Right.

Andy Greenberg

That was pretty much the opposite of correct. It turns out, I now have realized in this slow motion epiphany, that cryptocurrency is extremely traceable.

Michael Lewis

I can remember the proselytizers coming onto me and saying, "You've got to write a book about Bitcoin because it's better money." Then you went to go try to use Bitcoin, and it was clearly not better money.

It made you long for dollar bills if you tried to spend Bitcoin, but that was what was in the air. If you were hanging out with anybody who knew anything about Bitcoin, they said these things and you just why not believe them?

Andy Greenberg

It seems looking back, who could be this foolish? Because the whole idea of Bitcoin is that it's not guaranteed, or it's not accounted for by any bank or government. Instead, it's all laid out in the blockchain. Every single transaction is recorded in the blockchain. I knew that even back in 2011.

But the thing that made me and possibly even Satoshi Nakamoto, this mysterious creator of Bitcoin, think that it could nonetheless be anonymous or untraceable, is that the blockchain only records transactions between Bitcoin addresses. These long strings of 34 numbers and characters that seem meaningless and don't seem to be tied to anything identifying at all.

Michael Lewis

There's a distinction that needs to be made between anonymous and untraceable. You can keep it secret who you are, you just can't keep the transaction secret.

Andy Greenberg

I guess the best way to describe it is not even anonymous or untraceable, but rather pseudonymous if you want to use the nerdy term, which is that you could send money from one pseudonym, a Bitcoin address to another. It didn't seem like there was any way to pierce the veil of who is behind those Bitcoin address pseudonyms.

Even though you could see exact amounts of Bitcoin being sent from one pseudonym to the next, it still seemed like this just a dark basement full of money changing hands, but you didn't know between whom. That seemed secret enough.

Michael Lewis

Right. Do you think Satoshi actually thought that untraceability was a feature of this?

Andy Greenberg

It was in this email that Satoshi sent to a cryptography mailing list, that listed these bullet points of why you should read my white paper basically, which includes participants can be anonymous. Just to be fair, there is one participant who has remained anonymous, who is Satoshi Nakamoto.

Michael Lewis

Which is in itself, an amazing story that it's the only secret that's left in the universe who Satoshi is. Who's the first person who attempts to trace Bitcoin and identify the people behind the accounts?

Andy Greenberg

Yeah. This whole story of the ability to trace cryptocurrency begins, I would say, with Sarah Meiklejohn, this graduate researcher at the University of California, San Diego, who just embarked on it as a anthropological study at first. She wanted to see if she could figure out how many people are using Bitcoin, how many people are hiding behind these millions of Bitcoin addresses.

But she very quickly began to see that she could actually develop techniques to first just to cluster these addresses to show that sometimes dozens or hundreds, or sometimes even millions of these addresses belonged to a single person or service, or even a dark web marketplace.

Michael Lewis

How did she do that?

Andy Greenberg

The first trick is, sorry, this sounds really technical, but it's pretty simple, which is that in a so-called multi-input transaction to spends bitcoins from an address, you got to control the private key for that address. If you're sending bitcoins in one transaction from lots of addresses, you must control the keys for all those addresses.

That proves that one person or one organization, one service, controlled all those addresses. You can go back in time then and say, "Oh, all those addresses must have belonged to this one cluster. All those addresses were one person or one service." That's one trick.

Michael Lewis

This Sarah Meiklejohn is deducing this?

Andy Greenberg

Yeah, exactly. That's maybe the easiest trick, that it was an open secret that was a problem. But she applied it across the whole blockchain, and immediately was able to cut in half the number of possible identities.

And show that you could cluster enough of these addresses that you immediately could see that there were only half as many clusters as there were Bitcoin addresses just with that one trick.

Michael Lewis

Her first question was how many people are actually using Bitcoin, as opposed to I wonder if you can actually trace the transactions?

Andy Greenberg

I think so. I think she really approached this as a researcher like, "This is an interesting world. Let's see what we can learn about it, and who these people are." How many of them are is just the most basic question, perhaps. That multi-input transaction trick was really just one clustering technique. She came up with another one that was based on change making in Bitcoin transactions. This is another weird feature of Bitcoin, at least with a lot of wallets software, is that when you want to spend bitcoins from a Bitcoin address, you can't just spend part of them.

You have to crack open the whole piggy bank, and then basically send all the money at that address and then get back the change at a different address. That means that you see the money travel from one address to two. You can basically follow around this one wad of cash as bills are peeled off of it. It remains the same wad of cash in the same person's possession, even as it's spent slowly. That's another trick that allowed her to see, "Oh, that money still belongs to the same, original person." Then sometimes then that wad of cash ends up being sent to a cryptocurrency exchange.

Even back in 2013 when she was writing this, cryptocurrency exchanges were demanding know your customer information, your actual identifying information. That means law enforcement can send a subpoena to that exchange and get the identity. If you can track someone's money, if you can identify a cluster, and then find the paths from that cluster out to an exchange where they want to trade their bitcoins for dollars or vice versa.

Now the other way to do it is and she did this too, you can interact undercover with addresses in that cluster. You can see, "Oh, I'm putting money into a drug market and this is the address that I am interacting with. I know that address, and now I know that that address is part of a big cluster. That cluster must all belong to a big, black market for drugs."

Michael Lewis

I'm riveted by her and I'm interested in the kind of responses to her work she might have gotten from other researchers, but also the crypto community, who must have taken it as a full-frontal assault.

Andy Greenberg

Yeah. I tell these stories in the book. She went and spoke at one conference and just over breakfast that morning, she sat down with this cryptocurrency privacy researcher. They were talking about what are the privacy properties of cryptocurrency as it stands? This cryptographer posited, "Well, we need to develop systems such that law enforcement cannot track these transactions, no matter what crime may be taking place therein." Sarah responded, "Well, I don't know about that."

There definitely will be bad things that happen if you truly can never trace these transactions. Then he said, "Well, you eat babies then." Which I was like, "Wait, so there's nothing in between?" But that is how the conversation, and she remembers this very clearly. She was shocked and somewhat offended, and I think only then realized that this was not going to go over well in the traditional crypto world.

Michael Lewis

There's something bizarre and wonderful about lots of basically guys who think they're very smart, who have a perverse longing for secrecy.

Who believe they have created or encouraged a technology that enables the secrecy being totally exposed by a just truth seeking, young, female academic.

Andy Greenberg

Absolutely, but then she remains deeply ambivalent about it for her whole career. You said it's like a perverse instinct to try to maintain secrecy, but there are good reasons for financial privacy too, and financial surveillance is not always a wonderful thing. I was lucky in a way that Sarah is the person who represents that nuance and that complexity of the morality of surveillance, basically throughout the story. She actually finds some of the early big Bitcoin thefts and then traces them, and sometimes shows that that money ends up at an exchange.

For a law enforcement agency with subpoena power, they could go solve that crime right now. She puts that in the paper basically. Of course, this gets the attention of law enforcement, and she soon after has this meeting with a federal agency. She finds herself very turned off by the way that they are talking about privacy technologies, and the dark web and cryptocurrency. Also, her advisor jokes that she's become this cyber narc, as he puts it.

She finds herself torn between the privacy community, who doesn't particularly love her research, and the law enforcement agencies, who she doesn't entirely want to be a part of.

Michael Lewis

On Background will be right back. It's amazing to me that it takes five years from the time Satoshi creates Bitcoin for anybody, let alone an academic at UCSD named Sarah Meiklejohn, to figure out that Bitcoin is actually traceable. And a whole nother year for Michael Gronager to create a business called Chainalysis.

Andy Greenberg

Michael was reluctant to say to me like, "Oh, I just took all of Sarah's tricks." But he nonetheless says, "Yeah, I read Sarah's paper. It was fantastic."

I think Michael Gronager would say by then, certainly I would've not only come up with these tricks. But as he did, built them into a polished, automated piece of software that he could then sell to law enforcement.

Michael Lewis

We're now onto the real-world applications of Sarah's work and who takes it into the world. What's the first big case where it's cracked because of the tricks that Sarah turned up?

Andy Greenberg

Well, Tigran Gambaryan is in some ways the real protagonist of my book, and he is this fascinating character. He's a criminal investigator for the IRS and a forensic accountant, but also a computer nerd. He had looked at Bitcoin from the beginning and had similar thoughts to Sarah. There's a whole blockchain here. How could participants be anonymous, like Satoshi says? Then he was faced with this case where in the wake of the takedown of the first dark web, black market for drugs, the Silk Road.

He could see that this one DEA agent, who had worked on that case, was cashing out hundreds of thousands of dollars worth of Bitcoin of unknown origin. He guessed that this DEA agent, Carl Mark Force, had stolen it from the Silk Road, or had somehow enriched himself in the midst of this case. He just like, I don't know, emboldened by Sarah's paper, just sat down and started just clicking through Bitcoin addresses. Was able to trace this corrupt DEA agent's bitcoins back to the Silk Road, ultimately showing that Carl Mark Force, this DEA agent, had been selling law enforcement information to the creator of the Silk Road.

Michael Lewis

Being paid Bitcoin in exchange.

Andy Greenberg

Exactly. Also, trying to extort money from him.

Michael Lewis

This actually helps explain the tracking process. If this corrupt DEA agent had sold government information to the Silk Road bosses, and been given Bitcoin and just sat on the Bitcoin and never moved it, he would've been unfindable.

Andy Greenberg

Right. For Tigran Gambaryan, the case actually begins when he gets a tip from a cryptocurrency exchange, basically that this shady DEA agent is cashing out hundreds of thousands of dollars and is trying to do it under a pseudonym. That's the first giveaway. Then of course, at this point, the Silk Road, this dark web drug market has been seized.

The FBI actually has all of its Bitcoin addresses. I think that Carl Mark Force, this DEA agent, just never really reckons with the fact that all of this would be captured in the blockchain. He believed like everybody that Bitcoin was untraceable, and that in fact, it might be the perfect way to skim off the top, is that you're going to steal untraceable money. How is anybody going to catch you?

Michael Lewis

It's a funny idea that people might have been lured into criminal activity because they thought they had a secrecy that didn't exist.

Andy Greenberg

Well, it's this eternal idea about the internet that the anonymity there or the perceived anonymity unlocks your darkest desires. I think that is true sometimes, and it seems to have been true for Carl Mark Force. He was seduced by this false promise of anonymity to become a corrupt cop, and he wasn't alone. That's the crazy thing. Tigran Gambaryan then found this other sum of hundreds of thousands of dollars of Bitcoin, that people had noticed was missing from the Silk Road.

Everybody thought that it must be the same corrupt DEA e agent, but Tigran, who is now getting better at tracing cryptocurrency transactions by this point on the blockchain, figures out that it's another corrupt agent. The Secret Service agents based in the same Baltimore office as the DEA agent, Carl Mark Force, and amazingly, they were not even aware of each other's corruption. They did this independently as far as anybody can tell.

They were both just seduced by this same misunderstanding about Bitcoin being essentially anonymous money that anybody can just grab and steal, and nobody can catch them.

Michael Lewis

I feel like we're in an episode of The Wire.

Andy Greenberg

Yes.

Michael Lewis

There was this spectacular case called AlphaBay. Could you just describe that case and the tools that the investigators used to crack it and bring it down?

Andy Greenberg

When the Silk Road is taken down, the first market that combines the dark web and cryptocurrency to try to create untraceable, black market transactions, that leaves this power vacuum that's filled by one market after another. A lot of them run away with everybody's money. The administrators steal the money, what we call an exit scam. A couple of them are taken down by law enforcements.

Then finally, a new one surfaces called AlphaBay that seems to have made no mistakes and law enforcements around the world cannot find any way to identify its administrator, who goes by the handle Alpha02. AlphaBay eventually grows to be 10 times the size of the Silk Road, and is doing millions of dollars in black market transactions every day.

Michael Lewis

What things are being traded?

Andy Greenberg

AlphaBay's innovation, is that well, Alpha02, in fact, was a credit card fraudster originally, a traditional cyber criminal hacker. He has this idea to combine the cybercrime, fraud, credit card hacking world with the narcotics market on the dark web.

Creates this behemoth that sells both kinds of contraband of stolen data hacking tools like troves of credit cards, but also heroin and fentanyl, and methamphetamines and anything you can think of.

Michael Lewis

I could buy stolen data along with my heroin.

Andy Greenberg

Yeah. Why not?

Michael Lewis

What's the first case where it's really cracked just by cryptography?

Andy Greenberg

Chainalysis by late 2016 and 2017, has figured out basically how to map out AlphaBay's Bitcoin addresses across the blockchain. Has created this constellation of 2.5 million addresses that it knows belong to AlphaBay. But within that, it's still very difficult to identify any single person's transactions, not to mention, to try to identify the kingpin of this whole black market, Alpha02.

But these two FBI agents in Washington, DC, who asked me to just call them Ali and Erin, they had this idea of looking at those exit scams that I mentioned, where the boss of a dark web drug market just steals everybody's money and runs off of it. They thought of it this way. When an exit scam happens, freaks out in the whole dark web economy, they all start warning each other, "Don't store any of your bitcoins on a drug market, unless you're about to spend them, because the administrator can steal them at any time, and you got to be careful about this."

Everybody pulls out their money from those accounts. But the one person Ali and Erin realized, who would not have to worry about that, would be the boss of a dark web market, him or herself. They had this idea to just look across this whole AlphaBay cluster that Chainalysis had really assembled, and look for sums of money that had sat unmoved, like large sums, even as everybody else got spooked by exit scams.

Michael Lewis

Yeah. Suggesting a sense of security in those pools of money.

Andy Greenberg

Exactly. Or just really suggesting that that probably belongs to someone who is immune from an exit scam, and probably is therefore, a boss of a dark web market.

Michael Lewis

Or really dumb.

Andy Greenberg

Right. Yeah, that's also possible. They try this technique and they comb through all those AlphaBay addresses and finds several sums. But one in particular that is really big, has sat unmoved through exit scams and then is eventually parceled out, and trickles out to a cryptocurrency exchange where it's cashed out, and they send a subpoena to that exchange. Now, in the meantime, it turns out that the Fresno office of the DEA got this tip that in the earliest days that AlphaBay was online, its user forums it turns out basically leaked the email address of the administrator of AlphaBay.

This was back in 2014 when nobody was paying attention to AlphaBay that this email address, which was pimp_Alex_91@hotmail.com, was in the metadata of this email. But the Fresno office gets this tip and they start looking at that email address. They find other places where it has appeared in forums online, and they tie it to this French Canadian guy, Alexandre Cazes, who they then see has moved to Bangkok. Appears based on his wife's and his in-laws' social media posts, to own a Lamborghini, to have a villa in the south of Thailand, all this stuff.

They caught onto this, but they don't have any real confidence in their lead. They think it's almost like too good to be true. Maybe somebody is setting up this guy Cazes to look like Alpha02 even, maybe he's being framed. And just as they get this lead and they start to look into it, the results from that subpoena filed by Ali and Erin across the country in the FBI office, come back in. It reveals that cryptocurrency exchange account is owned by none other than Alexandre Cazes, essentially nailing this theory to a wall, whereas it before just hung by a thread.

Michael Lewis

Yeah. These stories are amazing stories, and the more you tell them, the more I wonder why anybody would try to do anything bad with crypto now. Well, you'd have to be a fool.

Andy Greenberg

Alexandre Cazes was not dumb. No matter how much we want to make fun of him, he did try to switch his currencies midstream. He tried to put them through mixers and other obfuscating tricks, some of which the FBI didn't even really want to tell me how they defeated, or Chainalysis, who has also become they are the masters at defeating these obfuscation tricks.

It's absolutely I think a good maxim that Bitcoin, especially of all cryptocurrencies, is the opposite of untraceable. But I think especially five, six years ago, somebody like Alpha02 would've thought that they could stay a step ahead. They would've thought that they were smart enough to win this cat and mouse game.

Michael Lewis

We'll be right back. I'm back with Andy Greenberg On Background. The question I wanted to revisit is, given what you've learned about how traceable crypto is, are you bewildered that we went such a long period where really smart people thought it wasn't.

How do you explain it? How do you explain the myth of untraceability that was all part of the Bitcoin sales pitch early on?

Andy Greenberg

Bitcoin was working, it had value. It had gone from $0 exchange rate to one, and that was amazing. It looked pretty private, and I think that that was enough for a lot of people to want it to be true enough.

Especially the kinds of people who use cryptocurrency wanted to believe, "Well, I can use this in just smart enough of a way to stay a step ahead." It was always this subjective judgments like, "Yes, of course cryptocurrency is traceable, but how traceable?"

Michael Lewis

I am curious to know, do you have a sense that the revelation that cryptocurrency transactions are very traceable and very hard to hide, has seeped into the consciousness of the people who use cryptocurrency, and they're now very wary of doing things, they're not making this mistake that they think that what they're doing is secret, but it actually isn't?

Andy Greenberg

Yeah. Now, I think yes, cryptocurrency users have wised up to what we all should have known all along, which is that blockchains make things very traceable. The other thing about blockchains is that they cannot be changed. That's the whole idea. It's like you cannot alter them or erase them. They're like records copied out the thousands and thousands of computers.

If you once believed that your cryptocurrency was untraceable and did something criminal with it, that is written in stone for any investigator to go excavate and use against you for years and years to come. IRS criminal investigators making massive cases against people accused of crypto crimes, sometimes even 10 years later based on blockchain evidence.

Michael Lewis

Is it basically impossible to use that crypto without being caught?

Andy Greenberg

I don't want to say it's totally impossible. I made this mistake 10 years ago. I believe that Bitcoin could be untraceable, so nobody should listen to me, but I don't want to rule out that there is some way to use cryptocurrency in an untraceable way.

It seems almost like the possibility is just vanishingly small. I am almost certain that whoever took this FTX money will be identified through cryptocurrency tracing, and we'll find out if that was Sam Bankman-Fried or some hacker in North Korea, or who knows.

Michael Lewis

That means whoever took the FTX money either did not understand what you understand, how traceable crypto is. Or maybe was playing some other game entirely, never intending to use the money, just that maybe the sole purpose of the theft was to create a theft.

Andy Greenberg

Or maybe they were just looking at their bank account dwindled to zero and their life savings evaporate, and because they work for FTX and they panicked. Tried to make themselves whole without really thinking about the consequences.

Michael Lewis

That sounds plausible, but now they realize they can't do anything with it, so it's just going to sit there.

Andy Greenberg

Right.

Michael Lewis

This half a billion dollars of unspendable Bitcoin that was stolen out of FTX, what would the Department of Justice need in order to seize it? They know it's there, they can watch it. Why can't they seize it?

Andy Greenberg

Well, let's see. Here's a few ways you could figure out who took that money. You see that the person who stole it is now keeping it at this address, you have a suspicion it's them. You seize their computer, you find the private key for that address on their computer. That's one way. You see them trying to cash it out at an exchange. They think that they've laundered it enough that they can use an exchange that has their identifying information, and they cash it out that way.

Or maybe they try to use a rogue exchange in another country, but you can still find that they had used their IP address or something to cash it out. Or maybe even you take down that exchange and you seize its servers, and you prove that they cashed it out there. Or maybe just to include the full list of techniques, you interact with their address in some way where you trick them essentially into revealing their address through the equivalent of a buy and bust. You know that address belongs to a certain person, and you know that address is where the stolen loot is being kept.

Michael Lewis

Who would be watching this pile of loot right now? What law enforcement types or Chapter 11 people, or how is it being monitored?

Andy Greenberg

Well, IRS criminal investigations, they have made this almost like their bread and butter to follow this money, to patiently wait for an opportunity to identify who is sitting on these giant piles of unspendable coins.

The FBI has done this too, but even beyond these law enforcement agencies and the DOJ who oversees them all, there is a whole industry of private sector tracers, starting with Chainalysis.

Michael Lewis

It's funny to think that one of the subtexts of crypto, or even the text of crypto from the beginning, was a way to operate outside of the purview of government, to be invisible to that surveillance.

And that crypto has become the government's best business. That it's been unbelievably profitable to the government to go chasing after big piles of stolen crypto.

Andy Greenberg

Certainly. It is very ironic that billions of dollars worth of Bitcoin, I think, still is sitting in the US Treasury waiting to be sold as the criminal proceeds basically. But also, I think just the crazier thing even than that, is just how well it has served the government as a trap, as a honeypot for people who thought that they could flout the government's financial surveillance.

People who thought that they could do really criminal things, and instead, it just caught all of them. Starting with two corrupt agents, but stretching to people doing truly abhorrent things with child exploitation, massive drug markets, and billions of dollars in thefts too.

Michael Lewis

Andy, since crypto was first invented, there have been all these stories about what it was for, and the story has changed along the way. Each time, it seems like crypto might be dead, another story arises.

Take us 10 years from now, what is the story that people will be saying about crypto? What it's for, how useful it is?

Andy Greenberg

Wow. Well, I've been waiting for you to tell me that in your book. I've never been that interested in the legitimate uses of cryptocurrency. I don't know, I don't feel like it's my job to figure out why anybody should want to use cryptocurrency today, because it's not exactly obvious. But I do think the one part of this that I really will be following in 10 years, is this cat and mouse game that continues.

People really may have invented a truly untraceable form of cryptocurrency already in the form of Zcash, or perhaps even other ones. Zcash really does seem like it might be an actual black box, truly anonymous form of digital cash for the internet, and that will be fascinating to watch. If there really is a true crypto anarchic coin out there and it gains adoption, then that's a world we've never seen before.

Michael Lewis

Great. This was really helpful. It was helpful to me apart from the podcast. It was really interesting to hear all this.

Andy Greenberg

Well, thank you.

Michael Lewis

I really appreciate you talking to me. Your book's great. Thanks for spending the time.

Andy Greenberg

Oh, it's my pleasure. Thank you.

Michael Lewis

Andy Greenberg is a senior writer for Wired and the author of Tracers in The Dark: The Global Hunt for the Crime Lords of Cryptocurrency. On Background is hosted by me, Michael Lewis, and produced by Catherine Girardeau and Lidia Jean Kott. Our editor is Julia Barton. Our engineer is Sarah Bruguiere. Recorded by Topher Routh at Berkeley Advanced Media Studios.

Our music is created by John Evans and Mathias Bossi of Stellwagen Symphonette. On Background is a production of Pushkin Industries. If you have any questions for me, just remember that we have the website, atrpodcast.com, where you can submit questions or complaints, or whatever you'd like to submit. That's atrpodcast.com. To find more Pushkin podcasts, listen on the iHeartRadio app, Apple Podcasts, or wherever you listen to podcasts.