operator onboarding · pure C · air-gapped

Mint your sovereign root.

Every high-ranking Purcius builder holds their own root key — born on your device, in airplane mode, split so no single loss is fatal, never touching a network.

The key that anchors your FQDN. You generate it, you split it, you hold it. No shared box, no vendor, no trust in anyone else.

Android app

Airplane-mode guard → mint → export each share separately → publish your _key line.

Download APK

3.3 MB · arm64 · CI-built from source. Enable “install unknown apps” for your browser, tap it, open. iOS follows.

Right now — Termux

The exact same pure-C ceremony, on your phone today. No app store.

Ceremony ↓

What it does

Born cold. Airplane mode = radios physically off. The root is generated on-device, offline.
Shamir-split. Your 64-byte root is split N-of-M (default 3-of-5). Scatter the shares; any 3 rebuild it, any 2 reveal nothing.
Wiped. The whole key is erased from memory the instant it's split. It lives only as shares.
Public out, secret stays. You publish only operator.pub + your _key.<fqdn> line. The private root never leaves un-split.
Pure C, no network permission — the app cannot phone home.

Mint on your phone tonight (Termux)

# online, once — self-contained source bundle
pkg install clang make
curl -LO https://purcius.net/genesis/purcius-genesis-src.tar.gz
tar xzf purcius-genesis-src.tar.gz && cd purcius-genesis

# ✈️  AIRPLANE MODE ON — confirm all radios off
make
./genesis-cli selftest              # must print PASS

./genesis-cli mint 5 3  out
#   -> out/operator.pub   out/_key.txt   out/share-01..05.share

Scatter the 5 shares to 5 separate places. Publish _key.txt + operator.pub. Then reconnect. Recover anytime with any 3 shares:

./genesis-cli recover out/operator.key out/share-01.share out/share-03.share out/share-05.share

Under the hood

A thin shell over the Purcius crypto substrate: ed25519 keypair + shamir GF(256) split/combine, both pure C, both tested, vendored self-contained. The app adds a UI and an airplane-mode guard — nothing more. Auth & key material are substrate (pure C) by rule, never a per-app concern.

Source: purcius-genesis-src.tar.gz — self-contained, builds anywhere.