Session Authentication
Session authentication is the two sides mutually confirming each other's identity while a connection is being established between the remote control and the receiver. If authentication fails, no session is opened and no command is processed. It requires a bidirectional link; on a one-way transmission mutual confirmation is technically not possible.
The typical flow is as follows: the remote control sends a connection request, the receiver generates a value that changes in every session and passes it across, the remote control produces a response to that value with the shared key, and the receiver verifies the response. Because the value is fresh in every session, recorded old traffic is of no use.
- Replay protection: the session-specific fresh value directly invalidates a record-and-replay attack.
- Mutuality: not only the receiver but also the remote control confirms that the other side is the correct receiver.
- Session lifetime: when the connection drops the session falls; new authentication is required before commands can be given again.
What this structure means for occupational safety is important: when the session falls the machine is left without commands and the timeout comes into play, taking the outputs to a safe state. In the XRF protocol used in AXI's HCT400 and HCT402 sets, session authentication is one of the features listed in the dump data.
Context in which this term is used: Wireless remote control installation: pairing, relay, safety