Privacy Policy - Halinhinan

1) Who we are

Halinhinan is provided by Saifullah Ahad ("we", "us", "our"). It helps neighboring households plan, witness, and reconcile turns on a shared irrigation channel.

2) What this policy covers

This policy explains the information Halinhinan handles on your device and the records you may deliberately exchange with another Halinhinan user nearby. The app has no account system or developer-operated backend.

3) Information stored on your device

When you create or join a channel, Halinhinan can store:

• the channel name, household names, gate positions, share fractions, cycle supply, and schedule;
• signed turn starts and ends, approximate water-depth bands, witness responses, disputes, resolutions, cycle closures, and membership or share approvals;
• public signing keys and pseudonymous record identifiers used to verify which enrolled household signed an event;
• app preferences such as limited preview, reduced motion, and optional app-lock settings; and
• if you set an app PIN, a random salt and one-way PIN verifier rather than the PIN itself.

Private signing keys are generated for this app in Android Keystore and are not included in exchanged channel records.

4) Camera use

Camera access is optional and requested only when you open the QR scanner. Frames are analyzed on the device to read Halinhinan exchange codes. Halinhinan does not save photographs or video, retain camera frames, or send camera content to us.

5) Nearby and QR exchange

Only when you choose an exchange action, Halinhinan can copy signed channel records directly to another nearby Halinhinan device:

• Local network: the apps discover and connect to each other on the same Wi-Fi network or hotspot. Android network and Wi-Fi permissions support this direct connection.
• QR codes: one device displays a numbered set of codes and the other scans them.

The developer does not receive these records. Signed events provide integrity and signer verification, but they do not make household names confidential during a chosen exchange. Use direct exchange only with an intended neighboring household and a trusted local network; anyone who can scan a displayed QR code may obtain the encoded record.

6) Biometrics and app lock

If you enable biometric unlock, Android performs the fingerprint or face check. Halinhinan receives only the success or failure result and never receives or stores biometric templates. Device PIN or pattern is not accepted as a substitute for the app's own PIN.

7) What we collect or share

We do not collect, sell, or use your channel records. Halinhinan contains no advertising, analytics, cloud storage, authentication, social-media, or crash-reporting SDK. It does not send app data to the developer or to an advertising or analytics company.

A record sent to another user through the explicit nearby or QR exchange is a user-directed device-to-device transfer. The receiving user keeps an independent local copy and controls that copy.

8) Permissions

• CAMERA: optional QR-code scanning.
• INTERNET, network state, Wi-Fi state, and multicast state: direct sockets and discovery between nearby devices on the same local network or hotspot.
• USE_BIOMETRIC: optional Android biometric app unlock.

Halinhinan does not request location, contacts, phone, microphone, notification, advertising ID, or storage permissions.

9) Retention, backup, and deletion

Channel records remain in the app's local database until you delete the local record, clear the app's storage, or uninstall the app. Cloud backup and device-transfer backup are disabled. “Delete local record” removes the channel, household, and event database from that device. Clearing app storage or uninstalling also removes app preferences and app-owned key material.

Deleting your copy cannot delete a copy that you previously chose to exchange to another device. The user of that device must delete their own local record.

10) Your choices

• Deny or revoke camera access in Android Settings and use local-network exchange instead.
• Do not start nearby sharing or display QR codes unless you intend to exchange the record.
• Enable limited preview, the dedicated app PIN, or biometric unlock in Halinhinan settings.
• Use “Delete local record,” clear app storage, or uninstall the app to remove local data as described above.

11) Children's privacy

Halinhinan is a general irrigation coordination tool and is not directed to children under 13. We do not knowingly collect personal information from children or anyone else.

12) Security limits

Halinhinan verifies exchanged events with digital signatures and preserves conflicting signed versions for review. No software or local exchange method can guarantee absolute security. Keep the device protected, use app lock when household names are sensitive, and exchange only with people you intend to include.

13) Changes to this policy

We may update this policy when Halinhinan changes. The current version and effective date will remain available at https://privacy.saifullah.ai/halinhinan.html.

14) Contact

For privacy questions or deletion requests, contact Saifullah Ahad at www.saifullah.ai@gmail.com.