Client authentication for private snap stores?

[Dan Kegel]

We might like to have snap stores which require a client to have a
certain certificate to be able to connect and download packages, just
as one can do with apt.

I think the way go works, the word 'Certificates' would be in the
source tree for snapd if this were already supported.... but I don't
see i there, which makes me think nobody's gotten around to supporting
the
idea of access-controlled snap stores.

Or did I miss something?