A coworker posted this article a couple days ago, this part really stuck out to me.
One thing that has always felt strange to me about the cryptocurrency world is the lack of attention to the client/server interface. When people talk about blockchains, they talk about distributed trust, leaderless consensus, and all the mechanics of how that works, but often gloss over the reality that clients ultimately can’t participate in those mechanics. All the network diagrams are of servers, the trust model is between servers, everything is about servers. Blockchains are designed to be a network of peers, but not designed such that it’s really possible for your mobile device or your browser to be one of those peers.
With the shift to mobile, we now live firmly in a world of clients and servers – with the former completely unable to act as the latter – and those questions seem more important to me than ever. Meanwhile, ethereum actually refers to servers as “clients,” so there’s not even a word for an actual untrusted client/server interface that will have to exist somewhere, and no acknowledgement that if successful there will ultimately be billions (!) more clients than servers.
For example, whether it’s running on mobile or the web, a dApp like Autonomous Art or First Derivative needs to interact with the blockchain somehow – in order to modify or render state (the collectively produced work of art, the edit history for it, the NFT derivatives, etc). That’s not really possible to do from the client, though, since the blockchain can’t live on your mobile device (or in your desktop browser realistically). So the only alternative is to interact with the blockchain via a node that’s running remotely on a server somewhere.
A server! But, as we know, people don’t want to run their own servers. As it happens, companies have emerged that sell API access to an ethereum node they run as a service, along with providing analytics, enhanced APIs they’ve built on top of the default ethereum APIs, and access to historical transactions. Which sounds… familiar. At this point, there are basically two companies. Almost all dApps use either Infura or Alchemy in order to interact with the blockchain. In fact, even when you connect a wallet like MetaMask to a dApp, and the dApp interacts with the blockchain via your wallet, MetaMask is just making calls to Infura!
These client APIs are not using anything to verify blockchain state or the authenticity of responses. The results aren’t even signed. An app like Autonomous Art says “hey what’s the output of this view function on this smart contract,” Alchemy or Infura responds with a JSON blob that says “this is the output,” and the app renders it.
This was surprising to me. So much work, energy, and time has gone into creating a trustless distributed consensus mechanism, but virtually all clients that wish to access it do so by simply trusting the outputs from these two companies without any further verification. It also doesn’t seem like the best privacy situation. Imagine if every time you interacted with a website in Chrome, your request first went to Google before being routed to the destination and back. That’s the situation with ethereum today. All write traffic is obviously already public on the blockchain, but these companies also have visibility into almost all read requests from almost all users in almost all dApps.