PubSub JWT Token signing not working

What does the rest of your code look like? JWT generation is only part of whats going on here.

I think the problem here is that you have a listen in there and a technically invalid send of *

As for

broadcast is expected and a * rule might not match

To send to a single channel

{
  "exp": 1503343947,
  "user_id": "27419011",
  "role": "external",
  "channel_id": "27419011",
  "pubsub_perms": {
    "send":[
      "broadcast"
    ]
  }
}

heres an example, which talks to the global segments of pubsub and config services