Android Unplugged

  As Android developers, understanding device security is essential to protect our apps and users. In this comprehensive guide, we’ll explore Android’s security architecture, including sandboxing, rooting and jailbreaking, and how to implement device attestation using SafetyNet and Play Integrity. We’ll cover each topic in detail, providing code snippets and best practices, following. What is Sandboxing in Android? Sandboxing is the security mechanism that isolates each app’s code and data from other apps and from the underlying system. In Android, this ensures that one app cannot freely read or modify another app’s private data or perform privileged operations unless explicit permissions or IPC channels are used.​ High-Level Idea Each app runs in its own isolated environment with: Its own Linux user ID (UID) and process. Its own private data directory (e.g., /data/data/<package_name>/ ). By default: One app cannot directly access another app’s files. An app cannot perfo...

  Inter-process communication (IPC) in Android is how different apps and system components talk to each other safely, even though each runs in its own isolated Linux process. Android achieves this with a kernel driver called Binder, wrapped in familiar APIs like Intents, Services, ContentProviders, AIDL, and Messenger.​ 1. Story first: apartments and the intercom Imagine every Android app as a separate apartment in a high-security building. Each apartment (process) has: Its own space (memory). Its own keys (UID/permissions). No direct access to other apartments. Yet, apps need to talk: Food-delivery app → asks Google Maps for routes. Camera app → sends photos to the gallery. Music app → asks the system if it can play over an ongoing call. Whenever this conversation crosses apartment boundaries (processes), you are doing IPC. Binder is the building’s intercom system that connects apartments and the building’s control room (system services).​ You already use IPC whenever you: St...