Exjobbspresentation: Key Management Solution for Post Quantum Transition

The advance of quantum computing poses a fundamental threat to today’s cryptographic systems. The American agency NIST advocates that all cryptographic systems transition to post-quantum cryptography (PQC) by 2035 and even earlier for more critical systems. Given the threat of harvest-now-decrypt-later attacks, there is a growing urgency for any system handling sensitive data to migrate to PQC in the coming years. This thesis investigates how the Swedish company Hyker should best migrate their end-to-end encryption (E2EE) platform to PQC. Their current platform relies on Intel SGX to make E2EE practical which itself depends on quantum-vulnerable primitives, necessitating a fundamental redesign of the architecture.

We propose a solution in which customized hardware tokens replace SGX to hold user key material and perform post-quantum operations. The solution is built around the Tillitis TKey hardware token and utilizes NIST’s post-quantum standards ML-KEM-768 and ML-DSA-65. A key challenge in using the TKey is the lack of persistent storage. This was addressed by a custom key management approach based on the TKey’s DICE-inspired Compound Device Identifier (CDI), which binds key material to both the integrity of the software loaded and the specific physical device. A proof-of-concept of this proposed solution was developed, which includes a quantum-resilient public key infrastructure where registered users, each provisioned with a TKey, can securely share documents. While the proof-of-concept demonstrates that PQC primitives can run within the constraints of a security token, there is a real limiting factor in the ML-DSA signing operation on TKey hardware, ranging from 2 to 30 seconds per signature.

Handledare LTH: Paul Stankovski Wagner

Handledare Hyker AB: Joakim Brorsson

Examinator: Thomas Johansson