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Android App Overview

The Android App included in this milestone serves as a demonstrator for Interstellar’s secure Web3 account lifecycle, showcasing how end-users can register, authenticate, validate transactions, and recover their accounts—all from a mobile-first interface.

Purpose​

The app is not intended as a production wallet, but as a reference implementation designed to:

  • Demonstrate the capabilities of the underlying runtime pallets
  • Interact directly with the TEE runtime for registration, authentication, and transaction validation
  • Showcase user flows involving Secure Elements (SE), attestation, and recovery

It also acts as the foundational layer for Interstellar’s future open-source mobile SDK, enabling integration with third-party wallets, dApps, or financial applications.

Key Features Demonstrated​

1. Mobile Account Registration​

  • Generates a new ECDSA keypair inside the device’s Secure Element (SE)
  • Displays hardware attestation metadata to the user
  • Submits a MOB-REG extrinsic to register the SE-bound mobile proxy account on-chain

2. Biometric-First Authentication​

  • Uses device-native biometric authentication (e.g., fingerprint or face recognition)
  • Unlocks the SE to sign application-layer payloads
  • Verifies attested keypair registration and presence on the chain

3. Trusted Transaction Validation Protocol (TTVP)​

  • Simulates a sensitive transaction or approval flow
  • Triggers a VCA Token execution which renders a randomized keypad and a transaction-specific message
  • Captures user-entered input and submits it through an AUTH extrinsic
  • The TEE verifies intent based on the circuit output and SE signature

4. Threshold-Based Recovery​

  • Registers backup items: NFC tag(s) and/or VCA-based secure file
  • Initiates recovery flow from the mobile interface
  • Verifies recovery item threshold (e.g., 2-out-of-3)
  • Rotates account keys and re-establishes account access securely

Architecture​

  • Built in Kotlin using Jetpack Compose
  • Integrates with Android Keystore and compatible Secure Elements
  • Communicates with the TEE runtime via RPC/WebSocket
  • Uses substrate-connect or a custom interface layer for submitting extrinsics
  • Includes a garbled circuit evaluation engine written in Rust, compiled as a native binary for Android
  • Includes a low-level visual cryptographic frame renderer, also written in Rust, which works in tandem with the evaluator to render secure digit segments and visual confirmation messages
  • Future support for WASM-based browser execution is planned

Developer Note​

This app is intended not just for milestone evaluation, but as a blueprint for developers who wish to:

  • Integrate Interstellar's authentication logic into their dApps or wallets
  • Build custom flows using the upcoming mobile SDK
  • Understand how biometric auth, SE signature, and visual confirmation integrate into a secure transaction lifecycle

Current Limitations​

  • Transaction validation screens may not render perfectly on low-end devices or emulators with limited GPU support
  • Secure Element signature integration is active, but full runtime verification (SE fingerprint validation) is planned for a future milestone

Summary​

The Interstellar Android App demonstrates how decentralized authentication and account lifecycle management can be securely delivered through a mobile-first interface. It anchors account abstraction, TEE execution, biometric authentication, and cryptographic recovery in a fully decentralized stack — ready to be extended into third-party applications and SDKs.