Franziskus Kiefer conducted a comprehensive security analysis for the XMTP-MLS protocol in the xmtp/libxmtp repository, focusing on the Harvest Now Decrypt Later (HNDL) threat model. He documented and assessed the forward security properties and limitations of HNDL, with particular attention to resilience against future quantum adversaries and post-remove security scenarios. Using his expertise in cryptography and security analysis, Franziskus produced detailed technical writing in Markdown that informed risk-aware design decisions for the protocol. His work provided in-depth documentation and risk assessment, aligning with the XMTP-MLS roadmap to reduce security risks and support the delivery of secure features.