DDSSEC12 — Avoid sending permissions as part of Authentication Handshake

The authentication handshake requires participants to exchange their permission files. This is done as clear text.

Visibility into the permissions file leaks information as to what the system Topic names are as well as what the application publishes and subscribes. This can be sensitive for some systems.

Aside form this sending this document is potentially expensive as the knowledge could be available on a separate channel.

The RTF should look share this information only with authenticated participants and possibly also avoid sending it if it is already known to the peer participant.

Related this is the fact that permissions are "monolithic" of you need to add a permission to a Participant you need to create and sign a new document. Would be nice to have some way to grant/propagate incremental permissions. E.g. something that could be bundled into the propagation of the Endpoint discovery data itself.