Songket

In recent times, our absolute reliance on centralized internet infrastructure has exposed a fatal vulnerability in how we communicate during crises. During the historic Bangladesh July Uprising and the catastrophic floods of 2024, millions of citizens were plunged into absolute darkness due to deliberate internet blackouts and infrastructural collapse. In these life-or-death scenarios, the total loss of connectivity meant that emergency rescue operations were severely delayed, families were agonizingly separated, and timely medical or disaster responses were rendered impossible. When traditional cellular networks, Wi-Fi, and ISPs fail—whether due to catastrophic natural disasters, power grid failures, or intentional state-sponsored internet shutdowns—ordinary citizens are left entirely voiceless, isolated, and incredibly vulnerable. The fundamental flaw is that modern messaging platforms rely on centralized servers. Without that centralized backbone, our standard communication tools become completely useless. The problem we are tackling is this inherent fragility in modern communication. We urgently need a resilient, decentralized, and censorship-resistant communication protocol that functions entirely off-the-grid. We must guarantee that affected communities can coordinate relief, share critical real-time alerts, and organize rapid rescue efforts seamlessly, even when the internet is entirely severed from the outside world.

To address this critical vulnerability in crisis communication, we built SongKet, a fully decentralized, off-the-grid mesh messaging application designed specifically to keep communities connected when traditional networks completely fail. SongKet leverages Bluetooth Low Energy (BLE) to construct a highly resilient, peer-to-peer mesh network. Instead of relying on vulnerable central servers or cell towers, every smartphone running SongKet actively serves as an independent routing node. Messages hop seamlessly from device to device, dynamically discovering the fastest route across the network to reach their destination. If a target user is temporarily out of range, the network's intelligent store-and-forward mechanism caches the encrypted message and delivers it automatically the moment a connection is re-established. At the heart of SongKet is an uncompromising commitment to absolute privacy, security, and anonymity. During periods of political unrest or disaster, communications are highly susceptible to malicious interception. To combat this, SongKet is entirely sniffing-proof. We implemented military-grade cryptography—utilizing X25519 for secure key exchange and AES-256-GCM for robust symmetric encryption. This ensures that all network traffic remains strictly end-to-end encrypted. No third party, including the intermediate mesh nodes forwarding the packets, can decrypt, read, or alter the contents. While typical mesh applications limit users to public broadcasting, SongKet introduces a highly secure Personal Direct Messaging (DM) feature. This enables users to establish private, one-to-one secure communication channels completely independent of the broader public mesh. This is vital for transmitting sensitive information such as specific GPS coordinates, urgent medical needs, or strategic organizational updates securely between two individuals. Furthermore, we recognize the severe physical risks users may face in hostile environments where their devices could be forcibly confiscated or compromised. To protect users in these dire situations, SongKet includes a covert Emergency Wipe Mechanism. By simply executing a rapid triple-tap on the application's logo, the app instantaneously and irreversibly destroys all local databases, cryptographic keys, and message histories, leaving no trace behind. Developed natively for Android using Kotlin and Jetpack Compose, SongKet is highly battery-optimized—a crucial requirement when power grids fail. By combining decentralized BLE mesh networking, uncompromisable cryptographic security, private direct messaging, and instantaneous data destruction, SongKet provides an essential lifeline. Whether facing natural disasters like the 2024 floods or political blackouts like the July Uprising, SongKet ensures the people remain connected, coordinated, and secure.

- Language: Kotlin - UI Framework: Jetpack Compose with Material Design 3 - Architecture: MVVM (Model-View-ViewModel) - Networking: Bluetooth Low Energy (BLE) for decentralized Mesh Networking - Cryptography & Security: X25519 (Key Exchange), Ed25519 (Digital Signatures), and AES-256-GCM (Symmetric Encryption) powered by the BouncyCastle cryptography library. - Async Operations: Kotlin Coroutines - Local Storage: EncryptedSharedPreferences (AndroidX Security)

We used Google Gemini as an AI coding assistant to help troubleshoot Android SDK and Gradle build errors, brainstorm technical architecture, and assist with drafting and refining our project's documentation and problem statements.