When a new cryptographic algorithm appears, a tension shows up: classical algorithms such as X25519 or Ed25519 have resisted attacks for years, but are vulnerable to a future quantum computer; post-quantum ones such as ML-KEM or ML-DSA resist quantum attacks, but are newer and less tested. Hybrid encryption resolves the tension: use both at once.
The idea in one sentence
Combine a classical and a post-quantum algorithm so that the system only breaks if both fail simultaneously.
A classical attacker would have to break the post-quantum algorithm; a quantum attacker would have to break the classical one and the post-quantum one. You gain security against the future without betting everything on a young algorithm.
Two places to apply it
