SimpleX Chat (world’s most private?) now connects desktop app with mobile app via quantum resistant protocol

SimpleX desktop app screen showing a list of chats on the left side, with an open chat conversation open in a pane to the right.

It sounds like a simple thing to do, but SimpleX is not a cloud based hosting, nor does it even have a common profile that anyone can just follow or connect to. Every friend being connected with, receives a unique invite address. There is no e-mail address or phone number used to register, so no-one can find or connect with you unless you send them their own unique invite.

Hence this linking has been keenly awaited for a while now.

How does it work? “The way we designed this solution avoided any security compromises, and the end-to-end encryption remained as secure as it was – it uses double-ratchet algorithm, with perfect forward secrecy, post-compromise security and deniability. This solution is similar to WhatsApp and WeChat. But unlike these apps, no server is involved in the connection between mobile and desktop. The connection itself uses a new SimpleX Remote Control Protocol (XRCP) based on secure TLS 1.3 and additional quantum-resistant encryption inside TLS.”

The downside of this approach is that mobile device has to be connected to the same local network as desktop. But the upside is that the connection is secure, and you do not need to have a copy of all your data on desktop, which usually has lower security than mobile.