For his next book, Michael Lewis wants to find out how investigators manage to trace the murky trail of illicit crypto. Cryptocurrency started with the dream of cash changing hands without a trace. But that dream has turned into a nightmare for many would-be criminals. A new field has emerged of data geeks and law-enforcement experts trying to find out who’s behind transactions on the blockchain. Michael calls up Andy Greenberg, senior cybersecurity writer for WIRED and author of “Tracers in the Dark: The Global Hunt for the Crime Lords of Cryptocurrency” to find out how investigators crack the code of crypto.
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Pushkin. Hello Against the Rules listeners, it's your long lost host, Michael Lewis. I missed 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, and 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. So what we're gonna 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. So welcome to on background from Against the Rules. I'm Michael Lewis. So the cryptocurrency movement arose on the back end of the two thousand and eight 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 from Chain Analysis estimated that there were fourteen billion dollars worth of shady dealings in two twenty one alone. Tracking cryptocrimes could be a nightmare, but there is a way, and I need to understand the nitty gritty of how it's done. So I called up Andy Greenberg, who's the senior cybersecurity writer for Wired, an 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 make a wonderful like 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. You know, I mentioned that I'm I've gotten very interested in the FTX story, and I'm curious do you share an interest? Have you been following it? Oh? Yeah, I mean I'm interested in it, but like 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, and that appears to have been a much more traditional kind of straight up theft by you know, we don't know who, like an insider, perhaps Sam Bankman freed himself maybe, or you know, was it hackers who just seized on the chaos of this meltdown to try to pull off a big heist. It's precisely the kind of heist that that your book suggests is a fool's errand because that bitcoin, that crypto is going to be traced and follow wherever it goes. Right, So, as soon as this happened, you know, I started calling my tracer friends and sources, I should say, and you know they were following this money in real time as it was being stolen. Basically, I mean, this is the crazy thing about cryptocurrency, which is that like, even if you can steal it, everybody can watch your getaway car make every turn, you know, through the city map, and like 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 but they can follow you as you do it, and it's going to be extremely hard for whoever took that money to liquidate it, to use it in any way without being identified, and then we'll find out if it was an insider or a thief. When you first got interested in crypto, in bitcoin, and you know, a completely innocent person asked you to explain to them what crypto was, what was your go to explanation? I think I would have 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, and 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. Right, that was pretty much the opposite of correct. It turns out, you know, I now have kind of realized, in this slow motion epiphany that cryptocurrency is extremely traceable. I can remember the proselytizers coming on to me and saying, you've got to write a book about bitcoin because it's it's better money. And then you went to go try to use bitcoin, and it was clearly not better money. It wasn't you know, it makes you long for dollar bills if you tried to spend bitcoin, but that was what was in the air. You're sort of like if you were hanging out with anybody who knew anything about bitcoin, they said these things and you just, you know, why not believe them? And it seems, you know, looking back, like, you know, who could be this foolish? Because the whole idea of bitcoin is that it's not sort of guaranteed or like it's it's not accounted for by any bank or government. Instead, it's all laid out in the blockchain, like every single transaction is recorded in the blockchain. And I knew that even back in twenty eleven. But the thing that made me and possibly even Sotoshi 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 like you know, thirty four numbers and characters that seemed meaningless and don't seem to be tied to anything identifying at all. So 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. I guess the best way to describe it is not even anonymous or untraceable, but rather pseudonymous if you want to like use the nerdy term, which is like that you could send money from one pseudonym a bitcoin address to another, and it didn't seem like there was any way to kind of pierce the veil of who is behind those bitcoin address pseudonyms. So even though you could see like exact amounts of bitcoin being sent from one pseudonym to the next, is still seemed like this kind of you know, just like a kind of dark basement full of money changing hands but you didn't know between whom, and that seems you know secret enough, right, So do you think Setoshi actually thought that untraceability was a feature of this There wasn't this email that Setoshi sent to a cryptography emailing list. It's you know, listed these bullet points of like why you should read my white paper basically, which includes participants can be anonymous, and just to be fair, you know, there is one participant who has remained anonymous, who is Sotoshi Nakamoto, which is in itself an amazing story that it's the only secret that's left in the universe who Setoshi is. So who's the first person who attempts to trace bitcoin and identify the people behind the accounts? Yeah, I mean this whole story of the ability to trace cryptocurrency begins, I would say with Sarah Michael John, this graduate researcher at the University of California, San Diego who kind of just embarked on it as a kind of anthropological study. At first, she wanted to see if she could figure out how many people are using bitcoin, how many people are kind of like 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 you know, dozens or hundreds or sometimes even millions of these addresses belonged to a single person or service or even like a dark web marketplace. How did she do that? The first trick is, sorry, this sound's really technical, but it's pretty simple, which is that a so called multi input transaction, to spend bitcoins from an address, you've got to control the private key for that address. So if you're sending bitcoins in one transaction from lots of addresses, you must control the keys for all those addresses. And that proves that one person or one organization, one service controlled all those addresses. So you know, you can kind of go back in time then and say, oh, all those addresses must have belonged to this one cluster, like all those addresses were one person or you know, one service. That's one trick, and so this is Sarah Michael john Is is deducing this, Yeah, exactly. And that's that's maybe the easiest trick that she It was sort of like kind of an open secret that was kind of a problem, but she was she kind of 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 immediately could see that there were only half as many clusters as there were Bitcoin addresses, just with that one trick. And her first question was how many people are actually using bitcoin? As opposed to I wonder if you can actually trace the transactions? I think so. I mean, 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 and how many of them are. It is just the most basic question. Perhaps that kind of multi input transaction trick was really just one clustering technique. She came up with another one that was based on change making in the bitcoin transactions. This is like another weird feature of bitcoin, at least with a lot of WATS software, is that when you want to spend bitcoins from a bitcoin address, you can't just spend like 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. So that means that you see the money travel from one address to two. You can basically follow around this one wad of cash as like bills are peeled off of it, and it remains the same wad of cash and the same person's possession, even as it's kind of like spent slowly. And that's another trick that allowed her to see like, oh, that money still belongs to the same original person. And then sometimes then that wad of cash ends up being sent to a cryptocurrency exchange. And even back in twenty thirteen when she was writing this, cryptocurrency exchanges were demanding know your customer information, like your actual identifying information, and that mean you've law enforcement can send a subpoena to that exchange and get the identity. So if you can like 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. And the other way to do it is like and she did this too, you can kind of interact undercover with addresses in that cluster and 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. I'm riveted by her, and I'm interested in the kind of responses to her work she might have gotten from other research, but also like the crypto community, who must have taken it as a full frontal assault. Yeah, I mean, I tell these stories in the book. Like she she went and spoke at one conference, and just over breakfast that morning, she sat down with this kind of cryptocurrency privacy researcher and they were kind of talking about, like, what are the privacy properties of cryptocurrency as it stands, and this cryptographer sort of posited, well, we need to develop systems such that law enforcement cannot track these transactions no matter what crime may be taking place, you know they're in and Sarah responded, well, I don't know about that. There are definitely there will be bad things that happen if you truly can never trace these transactions. And then he said, well you eat babies then, which I was kind of like, wait, so there's nothing in between, but that's that is how the conversations, and she remembers this very clearly. I mean, she was shocked and somewhat offended, and I think only then sort of realized that this was not going to go over well in the sort of traditional crypto world. 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 an or encouraged a technology that enables the secrecy being totally exposed by just truth seeking young female academic. Absolutely, I mean, but then she remains deeply ambivalent about it for her whole career. I mean, 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. And you know, I was lucky in a way that like Sarah is the person who represents that nuance and that complexity of the morality of surveillance. Basically throughout the story, she actually like finds some of the early big bitcoin thefts and then traces them and sometimes shows that that money ends up at an exchange and for a law enforcement agency with subpoena power, they could go solve that crime right now, and she puts that in the paper basically, so of course this gets the attention of law enforcement, and she soon after has this meeting with a federal agency, and she finds herself very turned off by the way that they are talking about privacy technologies and the dark web and cryptocurrency, and also her advisor kind of jokes that she's become this cybernarc, as he puts it. She finds herself torn between the privacy community who doesn't particularly like love her research, and the law enforcement agencies who she doesn't entirely want to be a part of. 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 Michael John to figure out that bitcoin is actually traceable, and a whole other year for Michael Groneger to create a business called chain analysis. I mean, Michael was reluctant to kind of 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. So I think Michael Groneger would say, like, by then, certainly I would have not only come up with these tricks, but as he did, like built them into a polished, automated piece of software that he could then sell to law enforcement. So we're now onto like the real world applications of Sarah's work and who takes it into the world. What's the first big case where it's because of the kind of tricks that Sarah turned up. Well, ch Green Dambarian is in some ways like the real protagonist of my book, and he is this like kind of fascinating character. He's a criminal investigator for the IRS and a forensic accountant and but also a computer nerd. And he had looked at bitcoin from the beginning and had similar thoughts to Sarah, like there's a whole blockchain here, how could participants be anonymous like Sotoshi says? And 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 there's one VA agent who had worked on that case was cashing out hundreds of thousands of dollars worth of bitcoin of unknown origin, and he guessed that this the EA agent Karl Mark Force, had stolen it from the Silk Road or had somehow enriched himself in the midst of his case, and so he kind of just like I don't know, emboldened by Sarah's paper, just sat down and started just clicking through bitcoin addresses and was able to trace this corrupt DA agents bitcoins back to the Silk Road, ultimately showing that Karl Mark Force, this DEA agent, had been selling law enforcement information to the creator of the Silk Road and being paid bitcoin and exchange exactly and also trying to extort money from him. So this is actually helps explain the tracking process. If this corrupt the 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 have been unfindable, right So Fatig Green Gambarian, the case actually begins when he gets a tip from a cryptocurrency exchange basically that this sort of shady DA agents is cashing out hundreds of thousands of dollars and is trying to do it under a suit of him. That's the first kind of giveaway and then of course, like at this point, the silk Road, this dark web drug market has been seized, so the FBI actually has all of its bitcoin addresses. I think that Karl Mark Forrest is the 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 then in fact it might be kind of like the perfect kind of way to skim off the top is that you're going to steal untraceable money, how is anybody gonna catch you. 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. Well, you know, it's like this kind of eternal idea about the Internet that like the anonymity there, or the perceived anonymity like unlocks your darkest desires. And I think that is true sometimes, and it seems to have been true for Karl Mark Forrest, like he sort of was seduced by this false promise of anonymity to become a corrupt cop and it wasn't alone. Like that's the crazy thing. T green Combarian then found like this other sum of hundreds of thousands of dollars of bitcoin that people had noticed was missing from the Silk Road, and everybody thought that it must be the same corrupt EA agent. But Tigren, 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 DA 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, and they were both just kind of, like, you know, seduced by this same the same misunderstanding about bitcoin being essentially like, you know, anonymous money that anybody can just grab and steal and nobody can catch them. I feel like we're in an episode of The Wire. Yes, there was a spectacular case called Alphabet. Could you just describe that case and the tools that the investigators used to crack it and bring it down? When the Silk Road is taken down, the first market this sort of 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, and they a lot of them, like run away with everybody's money. The administrators steal the money and what we call an exit scam. A couple of them are taken down by law enforcements, and then finally a new one surface is called Alphabet, 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 Alpha O two, and Alphabet eventually grows to be ten times the size of the Silk Road and is doing like millions of dollars in black market transactions every day, and what kind of things are being traded? Alphabet is sort of innovation? Is is that well? Alpha O two, in fact, was it kind of credit card fraudster originally a kind of traditional cyberchromin hacker. And so he has this idea to combine the cybercrime frauds credit card you know, hacking world with the narcotics market on the dark web and creates this behemoth that sells both kinds of contraband stolen data hacking tools like troves of credit cards, but also heroin and fentanyl and meth ampheta means and anything you can think of, So I can I can buy stolen data along with my heroin? Yeah, I mean why not. What's the first case where it's really cracked just by cryptography? So cha Analysis by late twenty sixteen and twenty seventeen has figured out basically how to map out Alphabet's bitcoin addresses across the blockchain and has created this like constellation of two point five million addresses that it knows belong to Alphabet. But within that it's it's still very difficult to identify, like in single person's transactions, not to mention to try to identify the kingpin of this whole black market Alpha O two. But these two FBI agents in Washington, DC, who asked me to just call them Ali and Aaron, 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, like when an exist scam happens, kind of 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've got to be careful about this. And so everybody pulls out their money from those accounts. But the one person Ali and Aaron realized who would not have to worry about that would be the boss of a dark web market him or herself. And so they had this idea to just kind of look across this whole alpha bay cluster that cha analysis 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. Yeah, suggesting a sense of security in those pools of money exactly, or just really suggesting that that probably belongs to someone who is immune from an exit scam. It probably is therefore a boss of a dark web market and or really or really dumb, right, Yeah, that's also possible. So they try this technique and they kind of combed through all those alphabet 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 whereas cashed out and they send a subpoena to that exchange. Now in the meantime, that turns out that the Fresno office of the DA got this tip that in the earliest days that Alphabet was online, it's user forums. It turns out basically leaked the email address of the administrator of Alphabet. This was back in twenty fourteen when nobody was paying attention to Alphabet. That this email address, which was pimp Underscore alex Underscore ninety one at hotmail dot com, was in the metadata of this email. But the First and office gets this tip and they start looking at that email address. They find other places where it has appeared in like forums online, and they tie it to this French Canadian guy, Alexander Kas who they then see has moved to Bangkok. Appears based on his like 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 and that, and they so they are they caught an 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 cause to look like Alpha O two. Even maybe he's being framed, and just as they get this leads and they start to look into it, the results from that subpoena filed by Ali and Aaron across the country in the FBI office come back in and it reveals that that cryptocurrency exchange account is owned by none other than Alexander Kaz, essentially like nailing this theory to a wall, you know, whereas it had before kind of just hung by a thread. Yeah, it's it's there. 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, like you'd have to be a you'd have to be a fool. I mean, Alexander kas was not dumb, no matter how much we want to make fun of him. He he did like try to you know, 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 Chain Alice, who has also become you know, they are the masters at defeating these obfuscation tricks. So you know, it's absolutely I think a good maxim that's Bitcoin, especially of all cryptocurrencies is the opposite of untraceable. But I think, especially like you know, five six years ago, somebody like Alphos who would have thought that they could stay a step ahead, They would have thought that they were smart enough to win this cat and mouse game. 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 people, really smart people thought it it wasn't And how do you explain it? How do you explain the kind of the myth of untraceability that was all part of the bitcoin sales pitch early on. I mean bitcoin was working, you know, it like had value. It had gone from zero dollars exchange rate to one, and that was amazing, and it looks pretty private, and I think that that was enough for a lot of people to want it to be true enough, and especially the kinds of people who use cryptocurrency wanted to believe, well, I can use this and just smart enough of a way to stay a step ahead. And it was always this kind of subjective judgments like yes of course, cryptocurrency is traceable, but how traceable? I am kind of curious to know. Do you have a sense that the revelation that cryptocurrency transactions are are very traceable and very hard to hide has sort of 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. Yeah, now I think yes, like cryptocurrency users have wised up to what we, you know, 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. There they're like records copied out the thousands and thousands of computers. If you once believe that your cryptocurrency was untraceable and did something criminal with it, that is written in stone for any investigator to go, you know, excavate ends and use against you for years and years to come. Iris criminal investigators making massive cases against people accused of crypto crimes, sometimes even like ten years later, based on blockchain evidence, is it basically impossible to use that crypto without being caught. I don't want to say it's totally impossible. I mean, I mean this mistake ten years ago. I believe the bitcoin could be untraceable, so nobody should listen to me, but it does. 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 you know, we'll find out if that was Sam Bakman freed or some hacker in North Korea or who knows. So that means whoever took the FTX money either did not understand, which 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, or maybe they were just kind of looking at their bank account dwindled to zero and their life savings evaporate, and because they work for FTX, and they panicked and tried to make themselves whole without really thinking about the consequences. That sounds that sounds plausible. But now they realize they can't do anything with it, so it's just going to sit there. Right, So there's 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? Well, let's see, here's a few ways you could figure out, Like who took that money. You see that the person who stole it is now keeping it 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. And at an exchange. They think that they've laundered it enough that they can use in exchange that has their identifying information and they cash it out that way, or maybe they try to use like a rogue exchange in another country, but you can still find that they'd use 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 you know, 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 a kind of the equivalent of like a buy and bust, and so you know that that address belongs to a certain person and that address is like where the stolen loot is being kept. Who would be watching this pile of loot right now? What law enforcement types or Chapter eleven people, or like, how is it being monitored? Well, I rs criminal investigations. They have made this almost like their bread and butter to follow this money, to pay eiently wait for an opportunity to identify who is sitting on these giant piles of unspendable coins. The FBI has done this too. And but you know, even beyond these law enforcement agencies and the dj who oversees them all, there is like a whole industry of private sector tracers, starting with chainalysis. You know, it's funny to think that one of the subtexts of crypto, or even the texts of crypto from the beginning, was it was a way to operate outside of the purview of government, to be invisible to that kind of surveillance, and that crypto has become like the government's best business, that it's been unbelievably profitable to the government to go chasing after big piles of stolen crypto. Certainly, I mean it's it is like very ironic that billions of dollars worth of bitcoin I think still is sitting in like the US treasury waiting to be sold as like you know, the criminal proceeds basically. But also I think, just like the crazier thing even than that, is just like how well it has served the governments as a trap, like as a honey pod for people who thought that they could flout the government's financial surveillance, people who thought that they could like do really criminal things, and instead it just caught all of them, starting with like two corrupt agents, but you know, stretching two people doing truly abhorrent things with child exploitation, massive drug markets, and yeah, billions of dollars and thefts too. So since crypto was first invented, they've been all these stories about what it was for, and the story has sort of changed along the way, and each time it seems like crypto might be dead, another story kind of arises. So take us ten years from now, what is the story that people will be saying about crypto, what it's for, how useful it is? Wow, Well, you know, I kind of been waiting for you to tell me that in your book. Like, 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 but I do think like the one part of this that I really will be following in ten years is this mouse game that continues. I mean, people really may have invented a truly untraceable form of cryptocurrency already, in the form of ze cash or perhaps even other ones. Ze cash really does seem like it might be an actual, you know, black box, truly anonymous form of digital cash for the Internet, and that will be fascinating to watch. I mean, if there really is a true crypto anarchic coin out there and it gains adoption, then you know, that's a world we've never seen before. Great. This was really helpful. It was helpful to me. Apart from the podcast, it was really interesting to hear all this well. Thank you. I really appreciate you talking to me. Your book's great. Thanks for spending the time. Oh it's my pleasure. Thank you. Andy Greenberg's 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 Katherine Gerardo and Lydia Jeancott. Our editor is Julia Barton. Our engineer is Sarah Bruguire. Recorded by Tofa Ruth at Berkeley Advanced Media Studios. Our music is created by John Evans and Matthias Bossi of Stellwagon. Symponette on Background is a production of Pushkin Industries. If you have any questions for me, just remember that we have the website atr podcast dot com where you can submit questions or complaints or whatever you'd like to submit. That's atr podcast dot com. To find more Pushkin podcasts, listen on the iHeartRadio app, Apple Podcasts, or wherever you listen to podcasts.