receiver keys
receiver keys are used by kast to verify signed broadcasts that you receive.
channel owners generate receiver keys when they create their channels. These keys can be freely distributed, though the channel owners must keep their corresponding sender key private.
kast supports automatic downloading of receiver keys that have been posted on web servers. After you add a receiver key for a channel to your node, your node will reject all broadcasts on that channel that have "bad" signatures (missing signatures, fake signatures, or signatures generated by a different sender key)