Privacy Policy

Last updated: August 27, 2026

Kinfount ("the App") is a private, end-to-end encrypted messenger. This policy explains what information is collected, how it is used, and what is never collected.

1. Information We Collect

• Phone number. Used as your account identifier. We do not verify it via SMS — it is entered manually during registration.
• FCM device token. A token issued by Google Firebase, used solely to deliver push notifications when you are offline. It is stored on the server and replaced each time you reinstall the App.
• App version. Your current app version is reported to the server on each launch. This is used to ensure compatibility between clients.
• IP address. Recorded incidentally in server logs when your device connects. Logs are not retained beyond standard operational needs.
• Encrypted media. Photos, videos, and files you send are encrypted on your device with AES-256-GCM before upload. The server stores the ciphertext only and cannot read the content.
• Contacts (optional, on-device matching). If you grant the Contacts permission, the App reads your device's address book (names, phone numbers, and contact photos) locally to show you which of your contacts are also using the App. To do this, your device downloads the list of cryptographic hashes (SHA-256) of the phone numbers of registered users from the server, and compares them locally against hashes computed from your own contacts. Your contact names, phone numbers, and photos are never uploaded to the server — only the match results stay on your device.

2. Information We Do Not Collect

• Message content. All messages are end-to-end encrypted using the Signal Protocol (X3DH + Double Ratchet). The server only ever sees encrypted envelopes and never has access to plaintext.
• Your contact list. Contacts are matched entirely on your device (see above) — the App never uploads your address book, contact names, phone numbers, or contact photos to the server.
• Location. The App does not collect or transmit location data.
• Analytics or advertising identifiers. The App contains no analytics SDKs, no advertising networks, and no tracking of any kind.

3. How Messages Are Stored

The server holds encrypted message envelopes for up to 30 days to deliver them when the recipient comes online. Once delivered, envelopes are deleted. Message bodies are never written to disk on the server.

On your device, messages are stored in a local SQLCipher-encrypted database. The encryption key is protected by the Android Keystore (hardware-backed where available).

4. Voice and Video Calls

Calls use WebRTC peer-to-peer connections. Call signaling (offer, answer, ICE candidates) is transmitted as encrypted Signal Protocol envelopes through the server. Audio and video streams travel directly between devices where network conditions permit, or through a TURN relay server otherwise. The server cannot access call audio or video.

5. Backups

If you choose to create a backup, the App can save an encrypted backup file to your Google Drive or local storage. The backup is encrypted with a password of your choosing. We have no access to your Google Drive or backup contents.

6. Third-Party Services

• Google Firebase Cloud Messaging (FCM). Used to deliver push notifications. Subject to Google's Privacy Policy.
• Google Drive (optional). Used only if you explicitly enable backup. Subject to Google's Privacy Policy.
• TURN relay server. A relay server used for call connectivity when direct peer-to-peer connection is not possible. It relays encrypted WebRTC traffic and does not log call content.

7. Data Sharing

We do not sell, rent, or share your personal information with third parties. Your phone number and device token are stored only on our server and used exclusively to operate the App.

8. Data Deletion

You can request deletion of your account and all associated data at any time — see our Account & Data Deletion page for how. Upon deletion, your phone number, device token, cryptographic keys, and all associated data are permanently removed from the server.

9. Children's Privacy

The App is not directed at children under 13. We do not knowingly collect information from children under 13.

10. Changes to This Policy

If we make material changes to this policy, we will update the date at the top of this page. Continued use of the App after changes constitutes acceptance of the updated policy.

11. Contact

If you have questions about this policy, contact us at: vitaly@gavrilov.cc

This policy applies to the Kinfount messenger application for Android.