A SCADA (Supervisory Control And Data
Acquisition) system is an industrial control and monitoring system for
national infrastructures. The SCADA systems were used in a closed
environment without considering about security functionality in the
past. As communication technology develops, they try to connect the
SCADA systems to an open network. Therefore, the security of the
SCADA systems has been an issue. The study of key management for
SCADA system also has been performed. However, existing key
management schemes for SCADA system such as SKE(Key
establishment for SCADA systems) and SKMA(Key management
scheme for SCADA systems) cannot support broadcasting
communication. To solve this problem, an Advanced Key
Management Architecture for Secure SCADA Communication has
been proposed by Choi et al.. Choi et al.’s scheme also has a problem
that it requires lots of computational cost for multicasting
communication. In this paper, we propose an enhanced scheme which
improving computational cost for multicasting communication with
considering the number of keys to be stored in a low power
communication device (RTU).