Encryption and Mutual authentication for Docker Containers?


I have two questions related to Docker container communication and security.

I have seen that container-to-container communication can be secured via encryption by enabling a secure flag.

Is this feature available for any stand-alone containers spawned via docker run on the default (or custom made) bridge interface?
Or is it only available in the swarm-mode amongst containers that are in the same overlay network?
And then, is there a similar feature to that of SSL mutual authentication amongst containers? As in to say, only containers with a certificate signed by a specific CA can talk to each other?

Or any other mechanism to restrict what containers can talk to which containers even when they are part of the same overlay network?