We Built a Signal Protocol Messenger. Then We Checked If It Was Legal in 5 Jurisdictions.

TL;DR: We checked Halonyx — our self-hosted E2EE messenger implementing X3DH + Double Ratchet — against the EU's Chat Control, US EARN IT Act, India's IT Rules 2021, the UK's Online Safety Act + Investigatory Powers Act, and the UN Cybercrime Convention. Here's the honest answer for each. When you implement end-to-end encryption from scratch, you spend a lot of time thinking about cryptographic threat models. Key substitution attacks. OPK exhaustion. WebRTC IP leakage. The adversaries you model are largely technical. At some point, you have to model a different kind of adversary: the legal one. We built Halonyx — a self-hostable E2EE messenger implementing the Signal Protocol (X3DH key exchange, Double Ratchet, Safety Numbers, WebTorrent P2P file transfer). The server architecturally cannot read your messages — not by policy, but because it holds no decryption keys and no plaintext. We wrote a STRIDE threat model across 17 attack surfaces. We did not write a legal threat model. So we did. This is what we found across five jurisdictions. None of this is legal advice. All of it is current as of July 2026, in a policy landscape that is actively moving. Quick Architecture Recap Before the jurisdiction breakdown, a one-paragraph recap of what Halonyx actually does, because the architecture is what determines the legal exposure. The relay server stores and forwards only AES-256-GCM ciphertext. It holds no private keys, performs no cryptographic operations on behalf of users, and has no mechanism to identify message content or originators. User identity is a pseudonymous 256-bit USID — the server stores only SHA-256(USID) . Files transfer peer-to-peer via WebTorrent; the server receives only a magnet URI. This architecture — which we call Federated Relay Architecture (FRA) — is what creates the legal situation described below. 1. European Union — Chat Control / CSAR Current status: No conflict with anything currently in force. The EU's Child Sexual Abuse Regulation (CSAR),