An object, which when modified, causes the secret encryption key used for messages sent on behalf of this user to/from the SNMP engine identified by usmUserEngineID, to be modified via a one-way function.

The associated protocol is the usmUserPrivProtocol. The associated secret key is the user's secret privacy key (privKey). The associated hash algorithm is the algorithm used by the user's usmUserAuthProtocol.

When creating a new user, it is an 'inconsistentName' error for a set operation to refer to this object unless it is previously or concurrently initialized through a set operation on the corresponding instance of usmUserCloneFrom.

When the value of the corresponding usmUserPrivProtocol is usmNoPrivProtocol, then a set is successful, but effectively is a no-op.

When this object is read, the zero-length (empty) string is returned. See the description clause of usmUserAuthKeyChange for a recommended procedure to do a key change.