sender keys

sender keys are used by kast to sign broadcasts that you initiate.

when you generate a sender key, a corresponding receiver key is also generated. The receiver key is the "public" portion of your key. You can freely give copies of your receiver key to others (those that will be receiving on your channel).

as long as you are the only one with access to the sender key for your channel (in other words, you keep the sender key "private"), only you can send broadcasts on your channel.