---
title: Identity
description: Manage Ed25519 peer identity and distinguish bind addresses, direct peer addresses, and relay circuit addresses.
---

Every authenticated connection binds a transport address to an Ed25519
identity. This guide covers key persistence and the address forms used for
binding, direct dialing, and relaying. Read
[PeerAddr and Multiaddr](/rust/concepts#peeraddr-and-multiaddr) first if those
types are new to you.

## Ephemeral identity

When no key is supplied, binding generates a fresh Ed25519 keypair:

```rust
let node = minip2p::Endpoint::builder()
    .bind_quic("127.0.0.1:0")?;

println!("peer={}", node.peer_id());
```

This is convenient for tests and short-lived tools. The `PeerId` changes on
every run, so previously shared peer and circuit addresses stop identifying
the restarted node.

## Persistent identity

Load 32 secret bytes from secure application storage and provide the
reconstructed keypair:

```rust
use minip2p::{Ed25519Keypair, Endpoint};

// Load 32 secret bytes from your own secure storage.
let secret: [u8; 32] = load_secret_from_secure_storage()?;
let identity = Ed25519Keypair::from_secret_key_bytes(secret);

let node = Endpoint::builder()
    .identity(identity)
    .bind_quic_dual_stack()?;
```

`load_secret_from_secure_storage` is application code, not a minip2p API.
Persist `Ed25519Keypair::secret_key_bytes()` with owner-only permissions or an
operating-system secret store. Never log or transmit the secret.

## Address vocabulary

### Bind multiaddr

Chooses a local socket but does not identify a peer:

```text
/ip4/0.0.0.0/udp/4001/quic-v1
```

Pass it to `bind_quic_multiaddr`.

### Direct PeerAddr

Adds the authenticated peer identity as the terminal component:

```text
/ip4/203.0.113.10/udp/4001/quic-v1/p2p/12D3KooW…
/ip6/2001:db8::10/udp/4001/quic-v1/p2p/12D3KooW…
/dns4/node.example.com/udp/4001/quic-v1/p2p/12D3KooW…
```

Pass a `PeerAddr` to `dial`, `connect_addr`, or builder methods that name a
relay or AutoNAT server.

### Circuit address

Names a target reached through a Circuit Relay v2 server:

```text
/ip4/198.51.100.5/udp/19876/quic-v1/p2p/<relay-id>/p2p-circuit/p2p/<target-id>
```

The relay must already hold a reservation for the target.

## Supported host components

The QUIC adapter accepts `/ip4`, `/ip6`, `/dns`, `/dns4`, and `/dns6`,
followed by `/udp/<port>/quic-v1`. A direct `PeerAddr` then adds exactly one
terminal `/p2p/<peer-id>`.

`PeerAddr::from_str` rejects a missing, repeated, or non-terminal peer ID.
Transport-specific dialing can also reject an address that parses but is not
a supported QUIC shape.

## Wildcards are not advertisements

`0.0.0.0` and `::` mean "bind all local interfaces." They are not routable
remote destinations. Replace a wildcard with a real interface or public
address before sharing it, or advertise a relay circuit address when the node
is private.

For automatic address sharing and dialing, see
[Discover peers](/rust/discover-peers).