Florian Maury
Florian Maury is a freelancer offering services as a software/system/security engineer and architect.
They also write a technical blog "Broken by Design" and host a podcast "Yakafokon" on Infrastructure as Code Security and DevSecOps practices.
In their spare time, Florian also contributes to free software, and they are an activist for animal rights.
Sessions
Twelve years after the public specification of the Signal protocol, almost all
instant messaging protocols have embraced the ratchet construct, granting perfect
forward secrecy and post-compromise security.
Whatsapp, Signal, OMEMO-based applications, Olm and Megolm-based applications,
or SimpleX Chat all use the Double Ratchet protocol. Olvid also uses a ratchet
protocol, although the construct is a bit different. And there are the stragglers
who insist on not using any form of perfect forward secrecy, such as Session or
Delta Chat. Of those, we will talk no more.
But since then, we have learned the hard way from some NSA executive that
metadata gets you arrested or killed. And so begs the question: how well are
protected our metadata by the various instant messaging infrastructures?
Signal claims one cannot hand over data one doesn't have. But how honest are
they about the metadata they do have, and that could be requested from them or
their hosting provider by a subpoena and sealed orders.
In this talk, we will explore some metadata available to Signal servers, Olvid
servers, Matrix/Element home servers and SimpleX Chat SMP queue servers. We will
then discuss the strategies that some of these applications have deployed to
limit metadata exposition, including those leveraging external transport security,
such as the use of Tor.