DDSSEC13 — Clarify sender identity validation for DCPSParticipantsSecure dispose and unregister samples

DDS Security 1.2 §7.5.1.6 requires a participant, after authenticating a remote participant, to process participant status changes (dispose or unregister) through DCPSParticipantsSecure rather than the ordinary DCPSParticipants topic.

Consider authenticated participants B and C. C sends a cryptographically valid DCPSParticipantsSecure dispose sample whose GUID identifies B. Does the specification require the receiver to reject the sample because its authenticated sending participant or built-in writer is C, while the disposed participant instance is B?

Please clarify the required relationship between the authenticated source, the secure built-in writer, and the participant GUID identified by a dispose or unregister sample. If the sample must be rejected, please state the validation rule and where it applies, including when discovery protection is configured as NONE.