IEC 62351 - Power Systems Communication Security 5:8.5: Part 5, 8.5 and following: authentication of critical messages (challenge-response and aggressive mode), ASDU protection and error handling

Critical ASDUs are authenticated by a challenge from the receiving station and a keyed response, or in aggressive mode by the sender including the authentication data with the message, with error handling and statistics for failures; the 2023 edition extends protection to encryption of ASDUs where the link warrants; the clauses beyond 8.4 are not held and are described from the mechanism's published design.