Challenge Data is pseudo-random data that is included in certain types of message associated with DNP3 Secure Authentication. The challenge data changes randomly, so increasing the security of the message’s content by making each message unpredictable.
ClearSCADA generates the random challenge data using FIPS 186-2 including Change Notice 1, a pseudo random number generator application used by the U.S. Federal government.
Use the Challenge Data Length field in the relevant DNP3 Security section of the ClearSCADA Server Configuration Tool to specify the number of bytes of pseudo-random data that is included in each message.
Specify the required random data length in the range of 4 to 40 bytes inclusive. The specified amount of random data is included in the relevant messages.