PTS2025

Usable end-to-end security with Delta Chat and Chatmail
2025-07-02, 14:00–14:35 (Europe/Paris), Amphitheater 122

Over the years, Delta Chat has matured to be an easy-to-use, secure,
and even fast decentralized FOSS messenger app for all platforms.
In this talk we discuss two key security architectures:

  • Autocrypt and SecureJoin key distribution protocols for achieving
    automatic end-to-end encrypted messaging safe against MITM attacks, and

  • the open-signup Chatmail server network which successfully uses strict
    cryptographic interoperability contraints (DKIM, OpenPGP, TLS)
    instead of IP-reputation and spam classification methods.

We also highlight the six independent security audits and analysis conducted so far.

Holger is a long-time FOSS contributor. He is co-creator of the python testing tool "pytest", the PyPy project, and since about 10 years engaged in decentralized messaging research and development.
He is one of the co-creators of the Autocrypt and SecureJoin protocols, as well as one of the maintainers of the "Chatmail" project which explores new and more secure ways to run secure e-mail server networking.

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