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.