There is one other -- admittedly esoteric! -- place where a NULL cipher would he useful: Amateur Radio applications.
By law, we are forbidden from transmitting encrypted traffic, yet there are use cases where integrity protection in the absence of data content protection would be of benefit. A very common case is controlling a remote repeater site. Using data integrity coupled with a client X.509 certificate means I can restrict access to the "control" service at the site. It's fine if people see the traffic in flight, since they won't be able to authenticate to do a replay or issue their own commands. This is a distinct improvement over existing control schemes, which typically use DTMF touch tone commands that anyone can trivially figure out. As I said, a very niche case. It has been done before, using IPsec AH, but that's extremely heavy weight, and a pain to configure and maintain. It also requires a full-on IP fabric, whereas TLS can be implemented directly on top of AX.25 sessions, which represent the vast majority of amateur radio packet data links (which I acknowledge puts this outside the realm of the Internet, and therefore the IETF). --lyndon (VE7TFX) _______________________________________________ TLS mailing list TLS@ietf.org https://www.ietf.org/mailman/listinfo/tls
