sl-messages

Message transport and encoding primitives for MPC-style protocols.

This crate provides:

• message: deterministic message IDs (MsgId), tags, headers, and message allocation.
• relay: async relay abstraction (Relay) with in-memory, buffered, and optional mux/websocket backends.
• signed: typed signed message verification helpers.
• encrypted: encryption scheme abstractions and message builders.
• setup (feature-gated): protocol participant setup, round tracking, and abort-message validation. Includes setup::keys with no-op key/signature types for trusted transports.

Features

Default features: fast-ws, mux, setup.

• setup: protocol-round helpers in sl_messages::setup.
• mux: relay multiplexer (relay::mux) for fan-in/fan-out message routing.
• fast-ws: websocket relay (ws::FastRelay) based on fastwebsockets.
• simple-relay: marker feature used by downstream integrations.

Basic usage

Build a message ID and message bytes:

use std::time::Duration;
use sl_messages::message::{allocate_message, InstanceId, MessageTag, MsgId};

let instance = InstanceId::from([1u8; 32]);
let sender = [2u8; 32];
let id = MsgId::broadcast(&instance, &sender, MessageTag::tag(1));

let msg = allocate_message(&id, Duration::from_secs(10), 0, b"payload");
assert!(!msg.is_empty());

Use the in-memory relay:

use std::time::Duration;
use sl_messages::{
    message::{allocate_message, InstanceId, MessageTag, MsgId},
    relay::{Relay, SimpleMessageRelay},
};

# #[tokio::main]
# async fn main() {
let relay = SimpleMessageRelay::new();
let mut c1 = relay.connect();
let mut c2 = relay.connect();

let instance = InstanceId::from([3u8; 32]);
let sender = [4u8; 32];
let id = MsgId::broadcast(&instance, &sender, MessageTag::tag(7));

c1.ask(&id, Duration::from_secs(5)).await.unwrap();
c2.send(allocate_message(&id, Duration::from_secs(5), 0, b"hello"))
    .await
    .unwrap();

let received = c1.next().await.unwrap();
assert!(received.len() > 0);
# }

Notes

• BufferedMsgRelay adds local buffering and predicate-based waiting (wait_for, wait_for_limited).
• Cancel safety of buffered waits depends on the cancel-safety guarantees of the wrapped relay implementation.

License

See LICENSE.