Ember: A Serverless Peer-to-Peer End-to-End Encrypted Messaging System with Per-Message Forward Secrecy over an IPv6 Mesh Network
Hamish Alsop1,*, Leandros Maglaras1,2,*, Naghmeh Moradpoor1
1 School of Computing, Edinburgh Napier University, Edinburgh, UK
2 School of Computing, De Montfort University, Leicester, UK
* Corresponding Author: Hamish Alsop. Email: 
; Leandros Maglaras. Email: 
Computers, Materials & Continua https://doi.org/10.32604/cmc.2026.082500
Received 24 March 2026; Accepted 17 August 2026; Published online 10 September 2026
Abstract
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, each with their own drawbacks, making the need for a direct, infrastructure-light secure messaging system a continuing concern. This paper presents
Ember, a serverless peer-to-peer messaging system providing end-to-end encrypted communication over a decentralised IPv6 mesh network. Ember combines an Extended Triple Diffie–Hellman (X3DH) initial key agreement with the Double Ratchet algorithm to provide per-message forward secrecy (FS) and post-compromise security (PCS) without any central key distribution service. Since per-message keys can remain in the MessageKeyStore after their associated ciphertext records are deleted, the forward secrecy and secure deletion guarantees are strictly bounded against a forensic adversary. The system 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, and integrates a time-to-live (TTL) mechanism that reliably deletes expired ciphertext records within approximately 100 ms of their nominal expiry. 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 a controlled dynamic evaluation that correlates instrumented application telemetry with link-layer packet capture, demonstrating that the Double Ratchet is correctly driven by direction-reversal-triggered Diffie–Hellman ratchet steps, that the verify-then-decrypt processing order is upheld for every inbound message, and that the Yggdrasil link layer presents an opaque, fixed-size, fixed-cadence traffic profile to a relay-adjacent observer. The evaluation also surfaces a precise residual forward-secrecy gap in the current implementation which is documented as a targeted remediation item. The paper closes by discussing limitations and future work.
Keywords
End-to-end encryption; secure messaging; peer-to-peer systems; forward secrecy; double ratchet; X3DH; decentralised networking; mobile security; data minimisation; IPv6 mesh
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