Ember: A Serverless Peer-to-Peer End-to-End Encrypted Messaging System over an IPv6 Mesh Network

A substantial body of research has focused on formalising what constitutes a ``secure'' messaging system, recognising that end-to-end encryption alone is insufficient to capture the full range of security, privacy, and usability properties that are expected by modern users. Several solutions have been proposed recently, including their own drawbacks, making the need for a direct secure messaging system a necessity. This paper presents Ember, a serverless peer-to-peer messaging system providing end-to-end encrypted communication over a decentralised IPv6 mesh network. Ember operates without central servers, enforces data minimisation through ciphertext-only local storage and time-based message expiration, and prioritises architectural clarity, explicit trust boundaries, and practical deployability on Android. The paper describes the system architecture, cryptographic design, network model, and security properties. Ember includes a ciphertext-only persistence model using an encrypted local database, ensuring that message plaintext is never written to disk. Through the integration of a time-to-live (TTL) mechanism for automatic message expiration, Ember enforces data minimisation on mobile devices. Ember is a layered and analysable system architecture with explicit trust boundaries separating user interface logic, cryptographic operations, storage, and networking components. The paper presents dynamic testing results demonstrating that no plaintext information can be recoverable from captured network traffic, and finally discusses limitations and future work.