{"slug":"android-signing","title":"Android signing keys","summary":"Every Android build is signed with the app's key. Create one in FluxNative or register your existing keystore, copy its SHA fingerprints, and never replace it after release without a plan.","body":"Android only installs an update over an existing app when both are signed with the same key. Google Play enforces the same rule. The key is the app's identity, so treat it carefully.\n\nOpen **Build**, choose **Android**, and find **Signing key**.\n\n## Option 1: let FluxNative create the key\n\nClick **Create signing key now**, or simply start the first build and it creates one. The key is stored encrypted with the project and used for every later build of this app. This is the right choice for a new app.\n\nCreating it before the first build is useful when you need the fingerprints early, for example to set up Google sign-in in Firebase.\n\n## Option 2: register an existing keystore\n\nUse this when the app is already published with a key you own.\n\n1. Click **Register signing key**.\n2. Upload the `.jks` keystore.\n3. Enter the key **alias**, the **keystore password**, and the **key password** if it is different.\n4. Save. FluxNative reads the key to check it before it is used.\n\nRegister it **before** the first build. If FluxNative already created a key, registering yours is a replacement.\n\n## SHA fingerprints\n\nThe panel shows the key's **SHA-1** and **SHA-256** with copy buttons. Google services need them:\n\n- **Firebase** and **Google sign-in**: add both fingerprints to the Android app in Firebase project settings.\n- **Google Maps** and other Google Cloud APIs restricted to Android apps: add the SHA-1 with the package name.\n- If Firebase is connected, you can ask the assistant to register the fingerprints for you.\n\n> [!TIP]\n> With Play App Signing, Google re-signs the app it delivers from Play with its own app signing key. Add that key's fingerprints too. Find them in Play Console, under **Test and release**, **App integrity**. Otherwise Google sign-in works in your APK but fails in the Play-installed app.\n\n## Replacing a key\n\n**Replace keystore** exists for the rare case where you must switch keys. Replacing it means:\n\n- phones with the old build installed cannot update to the new one; users must uninstall first,\n- Google Play rejects the new bundle unless the key change was arranged with Google,\n- fingerprints registered in Firebase and Google Cloud must be updated.\n\nReplacement is blocked while a build is running. The replaced key is archived, not shown again.\n\n> [!WARNING]\n> Do not replace the key of an app that people already have installed unless you know exactly why.","sectionSlug":"native-builds","sectionTitle":"Build for devices","updatedAt":"2026-09-23T22:51:25.250Z","previous":{"slug":"android-builds","title":"Android builds"},"next":{"slug":"ios-builds","title":"iOS builds"}}