With DNP3 Secure Authentication, two Session Keys are required. One Session Key authenticates data transmitted in the monitoring direction (from a DNP3 outstation to its DNP3 master); the other Session Key authenticates data transmitted in the controlling direction (from the DNP3 master to a DNP3 outstation).
Use the Session Key Length field in the DNP3 Master’s Security section of the ClearSCADA Server Configuration Tool to specify the length of both Session Keys.
Specify a Session Key length that is supported by each of the DNP3 outstations on your system. The minimum length that you can specify is 128 bits.
For systems on which ClearSCADA is the DNP3 master, ClearSCADA generates Session Keys of the specified length using FIPS 186-2 including Change Notice 1.
Further Information