The kid value can have an arbitrary format according JOSE specification, but Docker distribution expects a specific format (libtrust fingerprint) to work. This is not written in the documentation so far and is only mentioned in the libtrust source code itself.
Signed-off-by: Fabio Huser <fabio@fh1.ch>
Split the discussion of v2 authentication into two parts:
1) A specification of the handshake between the client, registry and
authentication service.
2) A description of how `docker/distribution` implements this using JWT.
This should make it clearer that `#2` is an implementation detail, and
that clients should regard tokens as opaque entities that only the
registry and authentication service should understand.
Signed-off-by: Matt Moore <mattmoor@google.com>
