HomeKit Accessory Protocol for OpenBSD

OpenHAP shows MQTT-connected Tasmota devices in the iOS Home app. An iPhone pairs with openhapd as a HomeKit accessory; openhapd uses MQTT to control the real devices.

The server is Perl code on the base system: a daemon, a configuration file in /etc, and rcctl. It does not need a cloud account or a separate appliance.

Design

Native to OpenBSD

OpenHAP uses base-system Perl and a short list of packages. The daemon runs as _openhap, starts from rc.d, and limits itself with pledge(2) and unveil(2).

Pairing and sessions

Pair-setup is an SRP-6a exchange over the RFC 5054 3072-bit group; pair-verify is X25519 with Ed25519 signatures. ChaCha20-Poly1305 encrypts the sessions with keys from HKDF-SHA-512. The messages are TLV8 and JSON over HTTP/1.1, and mdnsd advertises the service. This project supplies the SRP exchange and the framing; CPAN modules supply the primitives.

Devices as configuration

You declare the accessories in openhapd.conf(5), and the daemon loads them at startup. OpenHAP supports thermostats, heaters, switches, sensors, lightbulbs, and dimmers today.

Small enough to read

Each module has a manual page or a POD sidecar, and the tests are adjacent to the source in t/.

Quick start

git clone https://github.com/dickolsson/openhap.git
cd openhap
make deps
doas make install

After these steps, the daemon also needs a user, a configuration file, and an MQTT broker. Install shows each step. Manuals is the reference for the daemon, the control utility, and the configuration format. There is a page for each module for readers of the source.

Related projects

Three projects have their own repositories and documentation, because they are not related to HomeKit. Fugu holds the OpenBSD-style daemon utilities that the server uses. FuguVM installs and manages OpenBSD virtual machines under QEMU; this project uses it to run the tests. FuguWeb builds this website.