Lightning in x402 and Agent Payments | Ben Carman SLP779

Ben Carman (0:00)

The CEOs and companies of OpenAI and Anthropip are, in my opinion, very evil people, and I don't want to give them money, but sadly, their models are so good. I'm like, holy shit, China can make just as good models as America. And that was the beginning of 2024, so two years ago.

Stephan Livera (0:18)

Hi, everyone, welcome back to Stephan Livera Podcast. Rejoining me on the show today is my friend Ben the Carman from Spiral. He's a developer working on LDK and recently X4-02. So welcome back to the show, Ben.

Ben Carman (0:31)

Hey, thanks for having me again.

Stephan Livera (0:32)

So I saw the news about X4-02, and you made a contribution there around Lightning, surprisingly, or predictably, I should say. But tell us a little bit about that. And I guess maybe, I guess maybe contrast, because listeners might be familiar with the idea of L4-02, and they might have also heard of X4-02. What's the difference?

Ben Carman (0:50)

Yeah, so there's actually three of them. There's also something called MPP. But yeah, so L4-02 is kind of the system that all the Bitcoiners created, where it's like hyper designed for basically, I guess to start out, like, what are all of these trying to solve?

Stephan Livera (1:05)

Right, yeah, what is L4-02, right? What's that HTTP-402 code?

Ben Carman (1:09)

So yeah, that's like when you go to a website, sometimes we go like 404.found or like 400 back request. There's also a 402 payment required. This was originally added in the HTTP spec like forever ago, but we had no internet-native payments, so it was never really used anywhere. But now that we have Bitcoin and Lightning, Crypto, blah, blah, blah, we can actually use this. So a few years ago, Lightning Labs team and some other Bitcoiners made L402, which was like a hyper-designed version of this for Lightning where you just send an invoice in the 402 error code, and then if the person payments pays, they put the invoice preimage to prove that they paid, and then you could get whatever you paid for or something. And that worked, but then all the shit-corners are like, oh, we don't use Lightning, we need to make our own version. So they made their own version called X402, which Coinbase has really champions. And it kind of had like diverse ecosystems where like all of us Bitcoiners are making something, the shit-coin ecosystem is making something. I mean, this is like everything in Bitcoin, it kind of feels like this. And it kind of sucks because all of them support like many different coins and like they have like wrapped Bitcoin on like Solana and Ethereum and stuff. So they kind of can use Bitcoin, but you know, using Lightning is like far better for payment systems.

So we wanted to get, you just want to get Lightning adoption everywhere.

You know, if L402 is not going to scale or maybe not scale, but not get as wide adoption, X402 is getting more adoption, like we should just try to meet them in the middle and add Lightning support to it. So as far as Spiral, we've been working on like, you know, we want this agentic payment stuff to kind of take off. So it has a good potential way to get Bitcoin payment adoption. So like, well, let's just try to make a contribution here, get informed the X402 community about Lightning and try to get inside the spec. It's actually a lot harder than we expected because X402 is like not at all designed for Bitcoin or Lightning. It's very Ethereum, EVM kind of based. It's like all based, like in Ethereum, everything's like kind of accounts instead of like BTXOs.

So everything in it kind of assumes like you're spending from an account, but that doesn't work at all for Lightning or Bitcoin at all. So you kind of have to work with them to like basically add a whole new system into X402 that would allow for this. Basically, there's now like this exact mode, and that lets you just like basically kind of go to like an L402 workflow where you can send an invoice and then the user pays and you can use the pre-image to authenticate afterwards and get whatever you bought.

Stephan Livera (3:42)

Yeah, and give us just on that, give us an idea of how the flow would work. Like as I understand, there's a facilitator concept and like Coinbase is the, let's say the default facilitator, but you can have others. Talk us through a bit, like how does it work if you want to, let's say you are a merchant who wants to take an L, you know, an X402 payment, like how does it work?