jxs/enr

The enr project is a Rust library that implements Ethereum Node Records, essentially digital business cards for computers participating in the Ethereum network. These records hold key information about a node, like its IP address and port number, and they're cryptographically signed so other nodes can verify their authenticity. At a high level, an Ethereum Node Record is a small bundle of key-value data that gets a digital signature attached. Every record has a sequence number that goes up each time the record is updated, so other nodes can tell if they're looking at an outdated version. The record is tied to a specific cryptographic key pair, and any changes require re-signing with that key. The whole thing can be encoded as a base64 string, making it easy to share across the network. This library would be used by developers building Ethereum networking software, things like Ethereum clients, peer-to-peer networking layers, or any application that needs to discover and connect to other Ethereum nodes. For example, if you're building a wallet app that needs to find and communicate with Ethereum nodes, or a lightweight client that discovers peers on the network, you'd use this library to create, read, and verify the records that nodes use to announce themselves. What's notable is the flexibility around signing. The library supports two different cryptographic key types out of the box, the standard secp256k1 keys used across Ethereum, and ed25519 keys, which are popular in broader networking contexts. There's also a "combined key" mode that can handle records signed with either type, which is handy if your software might encounter nodes using different signing schemes. Developers can even plug in their own custom signing algorithms by implementing a specific interface the library defines. The project follows an official Ethereum specification called EIP-778, so it's built to be compatible with other implementations across the Ethereum ecosystem. That standardization matters because it lets nodes built with different programming languages and tools all understand each other's records.