“Device ID” can mean several different values
An app may use Android ID, an app-set ID, a Firebase installation ID, an app-created UUID or a value returned by its own registration endpoint. Android's identifier guidance gives these values different scopes and reset rules. The backend may store one value beside an account, token or public key and reject requests when that relationship changes.
We trace the value from its source to storage, serialization and the server call that registers it. We also check when it changes: reinstall, app-data reset, signing-key change, profile change or device reset.
Keys can be bound to the Android device
Android Keystore can keep key material outside the app process and can bind a key to secure hardware. The app may sign a server challenge with that key while sending the public key or attestation record during registration. Copying the request body does not copy the private key.
We map key creation, alias selection, signature parameters, challenge handling and server enrollment. If the protocol supports a portable software implementation, we recreate it in the client. If hardware-backed signing is a required server rule, the callable API uses a small Android signer and keeps every other part in Python and JavaScript/TypeScript.
Integrity state can join the same request
Play Integrity tokens can bind a verdict to request data and app identity. We keep that flow separate from account login and device registration, then reconnect the parts in the same order used by the app.
What you receive
The full APK becomes a callable API with Python, JavaScript/TypeScript and Postman coverage. It includes device registration, key generation, signatures, encryption and decryption, sessions, token refresh and all app workflows. Any Android runtime component has a clear API boundary and deployment guide.
Sources
Reviewed 30 August 2026 · SReverse research desk