Privacy Policy

Effective Date: April 30, 2026

At StealthLingo, privacy isn't just a feature—it's the foundation of our entire architecture. This Privacy Policy explains our practices regarding your data when you use the StealthLingo mobile application.

1. Zero Data Collection

StealthLingo operates on a strict 100% Offline-First and Zero-Knowledge basis. We do not collect, transmit, store, or sell any of your personal information, translations, voice recordings, or images. There are no analytics trackers, no crashlytics, and no hidden telemetry in our application.

2. How Your Data is Processed

• Translations: All text translations are performed entirely on your device using Google ML Kit local models. No text is ever sent to a remote server.
• Voice (Speech-to-Text): Voice recognition is handled by your device's native SpeechRecognizer.
• Images (Camera/Gallery): Images captured or selected for text recognition (OCR) are processed locally on your device. The images are never uploaded to the cloud.

3. Data Storage & Encryption

If you choose to save your translation history, the data is encrypted using AES-GCM Envelope Encryption before being saved to the local SQLite database. The Master Key required to decrypt this data is generated locally via CSPRNG and stored securely in your device's hardware-backed Keystore (Android) or Keychain (iOS). We have absolutely no way to access or recover this key or your data.

4. Third-Party Services

StealthLingo relies on device-native APIs and offline Google ML Kit models to function. When downloading a new language pack for the first time, your device will connect directly to Google's servers to download the model file. Once downloaded, the app requires no further internet connection.

5. Permissions Requested

• Camera: Required only if you use the OCR feature to translate text from images.
• Microphone: Required only if you use the Speech-to-Text feature to translate spoken words.

6. Changes to This Policy

We may update our Privacy Policy from time to time. Since our app does not communicate with a backend, any significant changes to our data practices will be reflected in the app updates via the Google Play Store.

7. Contact Us

If you have any questions or suggestions about our Privacy Policy, please contact us via the GitHub repository issues page.