The paper says ghost protocol has never been implemented, but wasn't it widely used on trump administration version of the signal-custom-client, which sent messages to a ghost account responsible for indexing and backup of plain text copies?
Good point. Most of this was written before the signal-custom-client thing happened, so it wasn't top of mind. We also considered "serious" systems, deployed en masse. Perhaps we should've included this as well.
Good point. Most of this was written before the signal-custom-client thing happened, so it wasn't top of mind. We also considered "serious" systems, deployed en masse. Perhaps we should've included this as well.