Bjoern Reiners
Björn is a Product Manager at BWI GmbH, Germany's IT service provider for the Bundeswehr, where he leads the BundesMessenger, the sovereign Matrix-based communication platform for the German armed forces. With over two decades of enterprise experience, he has made it his mission to build open, secure communication infrastructure that belongs to no single company and no single interest. He believes that digital sovereignty is not a product feature. It is a public responsibility.
Sessions
When you operate communication infrastructure for one of Europe's largest defense organizations, "good enough" is never good enough.
At BWI, we do not just run Matrix. We trust in the idea behind it: that secure, open communication should be a public good.
When we introduced Matrix into the Bundeswehr, we made a deliberate decision: everything, always, end-to-end encrypted. No exceptions, no fallbacks. That single switch revealed the hard problems. Olm and Megolm, built on the Signal Protocol, are the gold standard of modern encryption, but they were not designed for large rooms with thousands of participants at government scale. Those cracks are what brought us to MLS, the IETF standard built for exactly those harder problems: scalable group key management, stronger forward secrecy, post-compromise security. MLS does not just change how keys are managed. It changes how little the server needs to know. And that is not a side effect. It is a design goal. The less the server knows, the less it can leak, and required by VS-AP0024, the BSI guidance we operate under.
That settled the what. Rust settles the how. Not as a language choice, but as the foundation that makes formal verification of the functional core possible, and memory safety everywhere else a given.
We wrote MSC2546 ourselves, defining how MLS integrates into the Matrix protocol at the spec level. Now we are ready to share what happened next.
In this talk, Timm and David from BWI will show you what it takes to bring MLS into a real production stack: what changes in the SDK, what it means for backend modules, and how Rust becomes the common thread that holds it all together. Expect no polished success story. Expect honest engineering: what was built, where it broke, and what it cost. And at the end, the first thing they shipped with it. A new way to have a conversation that leaves no trace. Come find out when to change the locks.
Join our journey.
When you operate communication infrastructure for one of Europe's largest defense organizations, "good enough" is never good enough.
At BWI, we do not just run Matrix. We trust in the idea behind it: that secure, open communication should be a public good.
This talk traces that journey. It begins with our decision to adopt Matrix as the sovereign communication backbone for the German armed forces, and the architectural ambition that drives our work: a communication stack where the functional core is formally verifiable, and memory safety is a given everywhere else. An engineering target we are actively working toward.
As a first step toward that goal, working with Element, we brought a Rust-based cryptographic SDK into existence, the Matrix Rust SDK, a unified crypto platform shared across all our client applications, born from our security requirements and built to last. Rust was not an aesthetic choice. It was a deliberate decision rooted in memory safety, auditability, and the practical requirements of formal verification tooling.
Our work did not stop with the SDK. The same questions that shaped our cryptographic foundation led us to ask harder ones about the backend: what would a homeserver look like if security and formal verifiability were first-class requirements from day one, not afterthoughts? We have been exploring that question, and in this talk we want to share what we have learned so far, the decisions we faced, and where those explorations have taken us.
Join our journey.