Nym

The iroh-nym-transport crate routes iroh QUIC packets through the Nym mixnet, providing traffic analysis resistance by shuffling and delaying packets across a network of mix nodes.

This is useful when you need stronger metadata privacy than Tor provides; the mixnet obscures not just your IP address, but also communication patterns and timing.

Both iroh’s custom transport API and this crate are experimental. Expect breaking changes.

Installation

cargo add iroh-nym-transport

Usage

use std::sync::Arc;
use iroh::{Endpoint, endpoint::presets};
use iroh_nym_transport::NymUserTransport;
use nym_sdk::mixnet::MixnetClient;

let nym_client = MixnetClient::connect_new().await?;
let transport = Arc::new(NymUserTransport::new(nym_client));

let endpoint = Endpoint::builder(presets::N0)
    .clear_ip_transports()
    .add_custom_transport(transport)
    .bind()
    .await?;

Calling clear_ip_transports() disables QUIC over UDP so all traffic routes exclusively through the mixnet.

You can only connect to other endpoints that also have the Nym transport enabled.

Performance characteristics

The mixnet intentionally introduces latency and limits throughput as part of its privacy guarantees:

Metric	Direct QUIC	Nym mixnet
RTT	50–200 ms	~1–3 s
Throughput	10+ Mbps	~15–20 KiB/s

Nym is well suited for privacy-sensitive, latency-tolerant applications. It is not suitable for real-time communication or high-throughput file transfer.

Feature flag

Custom transport support must be enabled:

[dependencies]
iroh = { version = "*", features = ["unstable-custom-transports"] }