How Adam Back anticipated Bitcoin

I have a kind of security mindset, so I'd noticed That the university had some PIN codes on some of The doors. And I realized that this code is a 4-digit code, but basically there was no like Button to press, enter to let you in. If the code was 2345 it would let you in whether You typed 1234 or whether you typed 2345. So it occurred to me there would be a kind of Master code, like a single long sequence that Included all permutations of 4 digits. So I wrote a bit of software to create this and Printed it out on a single sheet of paper on 2/3 Of a sheet, and I tested it on another door that I wasn't supposed to have access to. And it worked, I got into the room. What was this room you got into? It was like, well, it was a kind of research lab With some parallel computers in it that was Accessible to post docs or something. Are we rolling, guys? Yeah, it's okay. Okay, fantastic. Let's play some Jenga! I'm not sure what the rules are, because it's Like… When I played it as a kid, I think it was you only Supposed to use one hand or finger and then there Were certain things about, you know, not doing The easy blocks by literally going from the Easiest block straight away. Okay. So let's jump to Hashcash. Was there an 'aha' moment during this process or Was it a long, arduous process similar to picking A lock?

I was interested in cryptography. So I happened to have been reading about hash Functions at the birthday collision. It's from the phenomena that if you have a room Full of people at a party or something, there's a Question which is how many people need to be in The room before there's 50/50 chance that there Are two people with the same birthday. You know, you think, well, it's going to be Related to 365, that's a number of days. But actually it's a lot smaller. It's like 23 people or something Counterintuitive. 23? Yeah. So low? It's because the people are like pulling a dice Out of a bag or something, right? So they've got random birthdays and as you get More of them, there are more potential birthdays For them to collide with. So overall, it ends up being a lot less than You'd expect. So anyway, with hash functions Like… You can take your time here. Oh, well, okay. I'm not sure that one's going to go. Okay, we've got one more left. There you go. So I was reading about hash Functions at this birthday collision. The hash functions are much more permutations Than number of birthdays, obviously, right. So there's trillions and trillions of Permutations. But it did occur to me that if you Found such a collision, it's like almost

Computationally impossible at the time Particularly, you could instantly prove it to Anybody. They could instantly verify this Enormous amount of work. And then I was also Running a remailer, which is a way to have Privacy for email, and there were people spamming Through it, which was a nuisance. And because it's related to anonymity, you Couldn't block their IP address or email and Stuff like that, right? So I was trying to think About a way to solve this spam problem that Didn't involve blocking IP addresses. So those two ideas came together. And so that's where Hashcash came from. Oh, that looks risky! There you go. Pressure's on. Okay! So when people see a finished system like Hashcash, it looks kind of simple and elegant, Right? And like, well, it's pretty simple, I can Understand that. And then their intuition is, you Know: "I could have built that." People were Trying to make electronic hash systems from Hashcash from after that, like 1997 and 1998 and So on. But it was quite hard to do. They didn't get implemented because they weren't Fully decentralizable. And as Bitcoin came to Adopt it, done by a massive amount of computers In 10 minutes, and that's obviously a much higher Amount of work. I held my breath here! You know, one of the nice things about Bitcoin is It's understandable at lots of different levels, Right? You can understand it from a user level or

From an economics level. It's surprisingly complex to fully appreciate all Of it, including the game theory and things like That. Obviously you're very busy with satellite projects . Put Bitcoin in space. Why do you need Bitcoin in space? There's a few reasons. One is because it's cool and you can. Why do anything, right? Yeah, sure. No, sh*t! Oops. I mean, I expected to lose there with the man that Is building blocks better than most people. And another is that you get some kind of privacy Because the receiving is anonymous. Yeah, just more Bitcoin. More Bitcoin. More blocks!