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Cryspen

Formal verification tools for security-critical software, including the open-source hax framework for verifying Rust code

Paris, FranceFounded 2021cryspen.comWebsite technologies

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Highlights

  • Young companyFounded 2021
  • New on EvolcAdded 2026-11-02

About Cryspen

Cryspen builds formal verification tools that establish security and correctness theorems for software, from high-level designs to deployed implementations. Its projects include hax, an open-source framework that verifies Rust code using multiple provers, and Spectrum, a specification-driven toolkit for developing high-assurance software from design to deployment.

Cryspen targets developers and organisations that build security-critical software. In June 2026 it spun off its cryptographic engineering work as CE Labs and refocused on formal verification tools, funded by the Spectrum EIC Transition project. A blog post on the company site announces that Cryspen is now named pereq.

Cryspen was founded in December 2021 by Karthik Bhargavan, Franziskus Kiefer and Jonathan Protzenko to apply formal verification tools developed at research labs such as Inria to commercial software development. Karthik Bhargavan is Chief Scientist and CEO. The company is headquartered in Paris.

Product: hax, an open-source framework for verifying Rust code with multiple provers, and Spectrum, a toolkit for high-assurance software development.

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