+When the +k (channel private key mode) mode is set the channel's
+default cipher and HMAC are not used. The private key (see /HELP KEY
+for help how to set the private key) defines the cipher and HMAC for
+the channel while +k mode is set. Also the +c and +h modes are ignored
+when channel private key is set.
+
+See also: CUMODE, UMODE, JOIN, KEY