Server ID bound to this registration.
Hex-encoded user public key (P-256 point from password).
Hex-encoded server private key for this user (P-256 scalar).
Hex-encoded server public key for this user (P-256 point).
Hex-encoded encrypted envelope (contains client's credential key).
Hex-encoded 32-byte salt for OPRF.
Server-side record created during PAKE registration.