{
  "slug": "cryspen",
  "name": "Cryspen",
  "url": "https://cryspen.com",
  "hq": "Berlin, Germany and Paris, France",
  "focus": "hax and libcrux: verified Rust post-quantum implementations; hax Lean backend for the Verified zkEVM program",
  "summary": "Cryspen builds hax, the Rust-to-proof-assistant translator, and libcrux, whose verified ML-KEM and ML-DSA ship in Mozilla and Signal. It is developing hax's Lean backend under an Ethereum Foundation grant and offers verification-driven reviews. The 2026 Verification Theatre paper documenting bugs outside libcrux's verified boundary is essential context for scoping its engagements.",
  "why_first": "",
  "services": [
    "Verified Rust implementations of classical and post-quantum primitives",
    "Protocol verification (Signal PQXDH, MLS)",
    "hax-based verification of client Rust code"
  ],
  "tools": [
    "hax",
    "fstar",
    "proverif",
    "ssprove"
  ],
  "evidence": [
    [
      "hax",
      "https://github.com/cryspen/hax"
    ],
    [
      "Cryspen ML-KEM verification",
      "https://cryspen.com/post/ml-kem-verification/"
    ]
  ],
  "fit": [
    "Choose Cryspen for Rust cryptographic libraries, particularly post-quantum, and insist on a written verification boundary."
  ],
  "rank": 6,
  "page": "https://sorryfree.com/firms/cryspen/",
  "updated": "2026-09-13"
}