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homelab-mfa/README.md
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# Homelab MFA
Biometric push-approval for your homelab logins. When you sign in through Authentik, your phone
buzzes — approve with a fingerprint, or deny with one tap. A self-hosted alternative to Duo /
Authy push, with **no third-party cloud** in the loop.
## How it works
1. You log in via **Authentik**. A flow step fires an **ntfy** notification to your phone with two
action buttons: **Approve** and **Deny**.
2. The buttons are `homemfa://approve?token=…` / `homemfa://deny?token=…` deep links that open this app.
3. **Approve** triggers a biometric prompt (fingerprint / face / device PIN). On success the app
POSTs `approve:<token>` to `ntfy.khodak.me/mfa-approve`; your Authentik flow is listening on that
topic and completes the login.
4. **Deny** POSTs `deny:<token>` to `mfa-deny` and blocks the login — no biometric needed to reject.
The activity is `showWhenLocked` + `turnScreenOn`, so an approval works straight from the lock screen.
## Features
- **Biometric gate** — `BIOMETRIC_STRONG` or device credential required to approve (deny is instant)
- **Lock-screen ready** — wakes the screen and shows over the keyguard
- **Self-hosted** — talks only to your own ntfy instance; no Firebase, no vendor cloud
- **Zero stored secrets** — stateless; each request carries a one-time token
- **Setup self-check** — a "Test Biometric" button confirms enrollment before you rely on it
## Screenshots
<p align="center">
<img src="docs/screenshots/setup.png" width="240" alt="Setup / ready screen">
&nbsp;
<img src="docs/screenshots/approved.png" width="240" alt="Login approved">
</p>
## Install
1. Download `homelab-mfa.apk` from the [latest release](../../releases/latest)
2. On your Android phone: **Settings → Apps → Install unknown apps** → allow your browser/file manager
3. Open the APK and tap Install
4. Open **Homelab MFA** and tap **Test Biometric** to confirm your fingerprint is enrolled
## Server side
You need:
- An **ntfy** instance reachable at `ntfy.khodak.me` (or change the host in `MainActivity.kt`)
- An **Authentik** flow that, on login, publishes a notification with the two `homemfa://` action
buttons, then waits on the `mfa-approve` / `mfa-deny` topics for the decision
## Requirements
- Android 9.0+ (API 28)
- A fingerprint, face, or device PIN enrolled