Transition must work
Quantum-resilient and backwards-compatible at once
Systems must adapt to new cryptography without disruption — or they will fail in transition.
Hybrid keys — quantum-resilient and backwards-compatible at once.
Six short explainers. Everything you need before Q-Day.
03 / Hybrid keys
Two keys, one credential, no partner coordination needed
Hybrid keys bundle a classical key (Ed25519 or X25519) and a PQC key (ML-DSA or ML-KEM) into a single DID Document. The result: a credential signed with both algorithms simultaneously.
Legacy systems that only understand Ed25519 can still verify it. PQC-ready verifiers check ML-DSA. As the industry transitions, the classical proof simply gets dropped — no re-issuance needed, no partner coordination required.
Ed25519 (classical)
ML-DSA-65 (PQC)
DID Multi-Key
W3C VC Data Integrity