KeyPlacement Enum
Where the private half of a key lives once a custodian is wired. This is the security posture, so a host names it at the call site and the library never picks one.
public enum KeyPlacementFields
Custodian 0
The private halves stay in the custodian. Every signature and every Content Encryption Key unwrap is a round-trip to it, and a compromised process holds no key to leak.
InProcess 1
The keys are minted in this process, sealed to the custodian's key-encryption key and shared as ciphertext through an IKeyRingStore. Signing then runs locally, so the custodian is touched once per key rather than once per token.
Remarks
Recorded rather than inferred from the registrations, so a host that layers its own key provider over the placement's does not change the answer. An enum rather than the name of the call that chose it: consumers dispatch on this, and a dispatch on a method name is a magic string that survives the method being renamed.