Crate enr

Ethereum Node Record (ENR)

This crate contains an implementation of an Ethereum Node Record (ENR) as specified by EIP-778 extended to allow for the use of ed25519 keys.

An ENR is a signed, key-value record which has an associated NodeId (a 32-byte identifier). Updating/modifying an ENR requires an EnrKey in order to re-sign the record with the associated key-pair.

User's wishing to implement their own singing algorithms simply need to implement the EnrKey trait and apply it to an EnrRaw.

This implementation uses a DefaultKey which implements signing for secp256k1 and ed25519 keys. With the libp2p feature enabled, this provides conversions from libp2p Keypair for libp2p integration.

ENR's are identified by their sequence number. When updating an ENR, the sequence number is increased.

Different identity schemes can be used to define the node id and signatures. Currently only the "v4" identity is supported and is set by default.

Features

This crate supports two features.

• serde: Allows for serde serialization and deserialization for ENRs.
• libp2p: Provides libp2p integration. Libp2p Keypair's can be converted to DefaultKey structs which can be used to sign and modify ENRs. This feature also adds the peer_id() and multiaddr() functions to an ENR which provides an ENR's associated PeerId.

These can be enabled via adding the feature flag in your Cargo.toml

enr = { version = 0.1.0, features = ["serde", "libp2p"] }

Example

To build an ENR, an EnrBuilder is provided.

Example (Building an ENR):

use enr::{EnrBuilder, DefaultKey};
use std::net::Ipv4Addr;
use rand::thread_rng;
use std::convert::TryInto;

// generate a new key
let key = DefaultKey::generate_secp256k1();

// pre-existing keys can also be used
let mut rng = thread_rng();
let key: DefaultKey = secp256k1::SecretKey::random(&mut rng).into();

// with the `libp2p` feature flag, one can also use a libp2p key
// let libp2p_key = libp2p_core::identity::Keypair::generate_secp256k1();
// let key: DefaultKey = libp2p_key.try_into().expect("supports secp256k1");

let ip = Ipv4Addr::new(192,168,0,1);
let enr = EnrBuilder::new("v4").ip(ip.into()).tcp(8000).build(&key).unwrap();

assert_eq!(enr.ip(), Some("192.168.0.1".parse().unwrap()));
assert_eq!(enr.id(), Some("v4".into()));

Enr fields can be added and modified using the getters/setters on EnrRaw. A custom field can be added using the add_key.

use enr::{EnrBuilder, DefaultKey, Enr};
use std::net::Ipv4Addr;

let key = DefaultKey::generate_secp256k1();

let ip = Ipv4Addr::new(192,168,0,1);
let mut enr = EnrBuilder::new("v4").ip(ip.into()).tcp(8000).build(&key).unwrap();

enr.set_tcp(8001, &key);
// set a custom key
enr.insert("custom_key", vec![0,0,1], &key);

// encode to base64
let base_64_string = enr.to_base64();

// decode from base64
let decoded_enr: Enr = base_64_string.parse().unwrap();

assert_eq!(decoded_enr.ip(), Some("192.168.0.1".parse().unwrap()));
assert_eq!(decoded_enr.id(), Some("v4".into()));
assert_eq!(decoded_enr.tcp(), Some(8001));
assert_eq!(decoded_enr.get("custom_key"), Some(&vec![0,0,1]));

Structs

EnrBuilderRaw	The raw builder for generating ENR records with arbitrary signing algorithms.
EnrRaw	The ENR Record.
NodeId	The NodeId of an ENR (a 32 byte identifier).

Enums

DefaultKey	A standard implementation of the EnrKey trait used to sign and modify ENR records. The variants here represent the currently supported in-built signing schemes.
DefaultPublicKey	A standard implementation of EnrPublicKey which has support for Secp256k1 and Ed25519 for ENR signature verification.
EnrError	An error type for handling various ENR operations.

Traits

EnrKey	The trait required for a key to sign and modify an ENR record.
EnrPublicKey	The trait required for a PublicKey to verify an ENR record.

Type Definitions

Enr	The default ENR type which implements the standard signing algorithms.
EnrBuilder	The default builder of ENR records which uses the standard signing algorithms.