Cockpit launches quantum hybrid key sealing under BSI standards

Cockpit’s Hybrid Key Sealing Meets New BSI Guidance

The German Federal Office for Information Security (BSI) has updated its technical guideline TR‑02102‑1, urging a shift to hybrid key‑exchange that pairs classical elliptic‑curve cryptography with post‑quantum algorithms such as ML‑KEM‑768 or ML‑KEM‑1024. Cockpit’s DuoKey SecureFolder implements exactly that approach, sealing folder keys with both P‑256 and ML‑KEM‑768 and positioning the solution as a concrete response to the BSI’s recommendation.

How the Hybrid Sealing Works

1. Three‑level key hierarchy – A hardware‑protected key‑encryption‑key (KEK) encrypts a 256‑bit folder key, which in turn derives per‑file AES‑256‑GCM keys via HKDF‑SHA256.
2. Dual public‑key registration – Each device and gateway registers a P‑256 public key and an ML‑KEM‑768 encapsulation key; private keys never leave the device.
3. Sealing process – Cockpit generates a fresh P‑256 key pair, performs an ECDH exchange, encapsulates a secret with ML‑KEM‑768, and combines both secrets with HKDF‑SHA‑384 to produce the sealed block (1218 bytes).
4. Defense‑in‑depth – If a quantum computer breaks P‑256, the ML‑KEM‑768 component remains secure, and vice‑versa. Downgrade attacks are blocked by requiring hybrid‑sealed keys at the gateway level.

Security Details Beyond the Seal

• File encryption uses AES‑256‑GCM in 64 KiB blocks with a random 96‑bit nonce.
• Header integrity is protected by HMAC‑SHA256, detecting any tampering instantly.
• Collaboration tokens (WOPI) are encrypted with AES‑256‑GCM and derived via HKDF, keeping user identity and file paths hidden.
• Editor signatures are verified on every call using RSA‑PKCS#1 v1.5 with SHA‑256, supporting regular key rotation.

What the BSI Still Recommends

While Cockpit’s hybrid sealing addresses key‑hand‑over, the BSI stresses that it is only a stepping stone toward full post‑quantum migration. It advises extending hybrid key exchange to TLS connections across browsers, Nextcloud instances, gateways, and other services, and recommends a comprehensive cryptographic inventory to eliminate any remaining purely classical schemes. Prioritizing long‑term confidential documents (10 + years) is especially important given the “harvest‑now, decrypt‑later” threat.

Practical Takeaways

• Immediate protection – By sealing keys with both classical and post‑quantum primitives, Cockpit offers a measurable increase in resilience against future quantum attacks.
• Compliance‑ready – The solution aligns with the latest BSI technical guideline, simplifying regulatory audits for German and EU customers.
• Roadmap awareness – Organizations should view hybrid sealing as part of a broader, phased transition to fully quantum‑safe protocols rather than a final solution.

Cockpit’s DuoKey SecureFolder demonstrates how practical engineering can translate emerging standards into deployable security, giving enterprises a concrete path forward while the quantum‑safe ecosystem continues to evolve.