Software Verification in Lean

Wed, 22 Apr 2026 00:00:00 +0000

This week in Paris, Cryspen is delighted to be co-hosting Software Verification in Lean 2026, a workshop and associated hackathon organized by the Beneficial AI Foundation and the Lean FRO.

SVIL 2026 brings together leading researchers and practitioners working on using the Lean proof assistant to formalize and verify real-world software. On Monday, I gave a talk on the challenges of verifying cryptographic applications, and the opportunities that are being opened up by the rapid innovations in Lean and by the emergence of AI-assisted formal proofs.

Helping Secure Signal's Post-Quantum Transition

Thu, 02 Oct 2025 00:00:00 +0000

Signal just announced the deployment of their new post-quantum ratcheting protocol, called the Sparse Post-Quantum Ratchet (SPQR), and Cryspen is proud to have contributed to the formal analysis of the design and implementation of this new Signal feature.

The seeds of our collaboration with Signal reach back to 2023, when Signal first published PQXDH, the post-quantum key establishment protocol that marked the beginning of Signal’s post-quantum transition. We helped Signal to formally analyze and improve PQXDH, resulting in a paper at Usenix Security. This time, Cryspen and Signal agreed to collaborate from the very beginning of the design process for SPQR all the way through to its implementation.

Signal on Cryspen

Software Verification in Lean

Helping Secure Signal's Post-Quantum Transition