TruthChain is a content authenticity platform designed to combat deepfakes and AI-generated misinformation. This Android application acts as the "Source of Trust," capturing images and cryptographically signing them using hardware-backed security before they ever leave the device.

• Hardware-Backed Security: Utilizes the Android Keystore System to generate asymmetric key pairs (EC/RSA) inside the device's Trusted Execution Environment (TEE). The private key never leaves the hardware.
• Content Authenticity: Captures photos using CameraX and immediately generates a digital signature of the image data.
• Tamper Proofing: If a single pixel of the image is altered after capture, the signature verification will fail.
• Local Buffer: Images are temporarily cached locally to ensure no data loss during the signing process.
• Seamless Upload: Automatically uploads the image, signature, and public key to the TruthChain Backend for verification.

• Language: Kotlin
• UI Framework: Jetpack Compose (Material 3)
• Camera: CameraX API
• Security: Android Keystore System (Hardware Security Module integration)
• Networking: Retrofit & OkHttp
• Offline Caching: Images and metadata are stored locally first, ensuring no data is lost during capture.
• Concurrency: Kotlin Coroutines & Flow

The app follows a Clean Architecture approach with MVVM:

1. Capture: User takes a photo via the in-app camera.
2. Sign: The app calculates a SHA-256 hash of the image bytes.
3. Encrypt: The hash is signed using the hardware-backed Private Key.
4. Transmit: The Image + Signature + Public Key are sent to the Spring Boot backend.
5. Sync: WorkManager detects network availability and sends the payload to the

• Android Studio Ladybug (or newer)
• Android Device (Minimum SDK 26 recommended for full Keystore support)

1. Clone the repository:
2. Open the project in Android Studio.
3. Sync Gradle files.
4. Connect a physical device (Emulators may not support all hardware-backed keystore features).
5. Run the application.

// Simplified Logic
val keyStore = KeyStore.getInstance("AndroidKeyStore")
val privateKey = keyStore.getKey(KEY_ALIAS, null) as PrivateKey
val signature = Signature.getInstance("SHA256withECDSA")
signature.initSign(privateKey)
signature.update(imageBytes)
val digitalSignature = signature.sign()