This is one of the rare use cases where the users should be identifying the servers they are connecting to. If your work is that spooky then a piece of paper with the expected key signature seems like a reasonable precaution.
There used to be that "key art" that was posted to make it more visibly distinct, but I think that feature got discontinued.
There used to be that "key art" that was posted to make it more visibly distinct, but I think that feature got discontinued.