Episode #5 – Cross-Chain Bridge Security – with Arjun Bhuptani of Connext

In this episode, I’m chatting with Arjun Bhuptani of Connext about cross-chain bridge security.

Watch this episode: Cross-Chain Bridge Security – with Arjun Kapoor of Kinetic Partners

Kerman:

Hey everyone. Today, we have Arjun Bhuptani from Connext. He’s the founder with us discussing everything bridges. So thanks Arjun for coming on.

Arjun:

Thanks for having me, Ryan.

Kerman:

Sweet. Well, let’s get this kicked off. So let’s just start really simple, what are bridges? And I think we can build from there.

Arjun:

Yeah. A bridge is a way to communicate between blockchains. So using any of a different set of mechanisms, relaying funds and/or data between two chains or chain and a rollup or two rollups. And then the piece that’s important is the different ways in which you can do that. So at the very simplest level, you could have some sort of fully custodial system, like a centralized exchange that is just taking funds off one chain and giving funds on another, and those have been around forever. And then you have more complex systems that kind of build up from there. So you can do things like atomic swaps, which have also been around forever, where you’re swapping one asset for another using HTLC contracts on chain, up to multisig bridges, which is the way that a lot of the bridges that are out there in the world right now work today. And then to more complex constructions, like optimistic bridges or client bridges, which are trustless mechanisms to have fully expressive communication between [inaudible].

Kerman:

Sure, so it feels there’s two vectors. Well, first question is, is there a difference between bridges that communicate data versus that hold money? Or are they more or less the same thing?

Arjun:

Yeah, that’s a good question. So I think what we are seeing right now is the bifurcation of different bridges into messaging layers and liquidity layers, because people are realizing that it makes sense to separate those things out. In theory, there isn’t actually any difference. The primary difference is really just, in one case, you’re having to bootstrap a bunch of liquidity, which is a secondary step. You’d basically need liquidity on a given chain to be able to send assets on that chain. Versus in the other case, you’re just sending a message, and that message could be mint an asset. But when you mint your own asset it’s basically creating a wrapped or representative version of the asset that you had on a second chain.

So I think, it’s like, these are two different things only in the sense that they have different requirements. And assets are such an important category of things for blockchains that it’s worth special casing them, but they’re not so different in the sense that they’re still underpinned by the same core mechanism. And most of the time, the liquidity and messaging layers are intertwined anyway.

Kerman:

Sure. So the way that I basically interpret that is a messaging bridge is a poor man’s bridge, because it has no defense ability because it…