A control object used to change a specified SNMPv3 user's authentication key via a Diffie-Hellman key exchange rather than sending the key directly. It lets an admin rotate another user's authentication secret over the wire without ever exposing the actual key material, even to eavesdroppers. An NMS performing a scheduled key rollover would SET this object with its DH public value to derive and install a new authentication key for that user's row.