Public keys are conveyed with their integrity and authenticity protected: in a certificate from a trusted CA meeting this Domain's CA requirements, with a hash validated over a separate channel, with an ISO 16609 MAC, inside an SCD, or encrypted; a self-signed certificate is never the sole authentication, and root certificates go directly into the POI device at manufacture, never remotely afterwards.
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.