hm-net

hm-net is experimental station software and a research protocol for delay-tolerant amateur-radio messaging: mail, chat, forms and group bulletins over HF and VHF/UHF packet, ARQ modems (VARA, Mercury, ARDOP) and authenticated internet links. It is a federated network of peer stations: every operator runs their own node and chooses whose keys to trust. There is no central server. Content is in the clear, as amateur rules require; every identity is authenticated with Ed25519.

hm is the command's working name until the project has a settled one.

A shared radio channel is scarce, half-duplex, lossy, and open only some of the time. hm-net treats airtime as the resource that matters:

• Store and forward with custody. A message moves one hop at a time, handed on only against a signed receipt; a path that is closed now is waited for, or gone around. The origin marks a message Delivered only on the destination's signed end-to-end receipt.
• Beliefs, not snapshots. Each station learns, by Bayes' rule, whether each path is within reach, when in the day it opens, how many frames it loses, and how well each custodian delivers, from beacons heard and missed, acknowledgements, and receipts that came back or did not; and it checks the chances it gives against how its handoffs ended, correcting them where its models err.
• Decisions by expected utility. Send now, wait for an opening, or go through a relay, over whichever bearer: the route whose chance times the value of arriving then, less its expected airtime, is best, and holding the message is always an option. Airtime is priced higher the busier the channel, so stations back off together.
• Fountain-coded transfers. RaptorQ bursts sized by the expected airtime to finish; a doubtful path is probed before it is sent a burst.
• Bounded control traffic. Beacons and control messages keep to a fixed share of the channel however many stations share it.

In simulation, five real stations on a week of fading, diurnal HF deliver 240 of 240 messages at 6 % channel occupancy, half within 1.4 hours of the earliest possible, each transmitter keyed about 1 % of the time and never for much more than 20 s at once; see results.

cargo install --path crates/hm-cli     # Rust 1.90 or newer
hm setup                               # key, station.toml, radio or internet
hm whoami                              # give this line to the other station
hm trust add "SO5KM 8a1e…"             # and add theirs
hm node                                # the station: open the web page it prints

Setting up a station covers each step, the radio (Direwolf, hardware TNCs, the built-in modem), ARQ modems and internet links.

Everything is in docs/:

• Operating: setup, settings, web page and API, radio, modems, internet, a lab of four stations.
• Design: overview, architecture, models, routing, transfer, custody, control plane, and what is new, and why.
• Evidence: simulation, results, testing.
• Reference: the specification, with test vectors.

Wire version 0: the format and the crates still change. The protocol and the daemon are implemented and tested in simulation and on localhost; the first multi-hop on-air trials are next (plan), and their measurements will tune the models and limits. The built-in web server does not terminate TLS; use a reverse proxy, VPN or SSH tunnel for remote access.

cargo test --workspace
cargo clippy --workspace --all-targets -- -D warnings

More in testing.

MIT or Apache-2.0, at your option.