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 How to install ↓

3.3 MB · arm64 · pure C.

iOS app

Same SwiftUI ceremony over the same pure-C substrate. Apple requires a signed build.

How to get it ↓

Via TestFlight / Xcode. Source included.

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.

Install on Android

Download the APK. Tap Download APK. Chrome may warn “this type of file can harm your device” — it’s your own app; tap Download anyway / OK.
Open it. Pull down the notification shade and tap the finished app-debug.apk — or open Files → Downloads and tap it.
Allow this source. Android says installs from this source are blocked. Tap Settings → turn on Allow from this source (this authorizes the app you downloaded with — Chrome or Files) → press Back. (Android 7 and older: Settings → Security → enable Unknown sources.)
Install. Tap Install. If Play Protect prompts, tap Install anyway (not signed by Google — signed by our build).
Open. Tap Open. On launch it self-tests the Core — you’ll see ✓ Genesis Core selftest PASSED.
Mint. Turn on Airplane Mode (the app won’t mint until it’s on). Enter your FQDN → MINT ROOT → export each share to a different place → publish your _key line. Done.

Any recent 64-bit Android phone. Nothing to take on trust — the app declares no network permission; verify against the source bundle below.

Install on iOS

Apple won’t sideload a raw file the way Android takes an APK, so iOS needs a signed build. Two paths:

TestFlight — best for onboarding builders: a signed build, an email invite, tap Accept in the TestFlight app. Available once the build is signed to the Purcius Apple team.
Build it yourself — the full Xcode project ships in the source: brew install xcodegen → cd ios && xcodegen generate → open in Xcode, set your Team, Run on your device.

Same pure-C substrate, same ceremony. iOS can’t read airplane-mode state, so the app blocks minting while any network is up — turn on Airplane Mode and it goes green.

Mint on your phone (Termux)

Tap Copy on each line, paste into Termux, run. Do 1–2 online, then go airplane mode.

1 · install the toolchain

pkg install clang make

2 · download the self-contained source + unpack

curl -LO https://purcius.net/genesis/purcius-genesis-src.tar.gz

tar xzf purcius-genesis-src.tar.gz && cd purcius-genesis

✈️ 3 · TURN ON AIRPLANE MODE — confirm every radio is off

4 · build & prove the core (must print PASS)

make && ./genesis-cli selftest

5 · mint — replace your-fqdn with yours

mkdir out && ./genesis-cli mint 5 3 your-fqdn out

Writes out/operator.pub, out/_key.txt, and out/share-01…05.share. Scatter the 5 shares to 5 separate places, publish _key.txt + operator.pub, then reconnect.

recover later — 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.