Abstract This paper presents and evaluates an advance hybrid key management architecture for supervisory control and data acquisition (SCADA) networks (HSKMA), which supports all three types of communications: unicast, multicast, and broadcast. The HSKMA is based on the elliptic curve cryptography and symmetric cryptography. While the elliptic curve cryptography is used for communication between master station unit (MSU) and sub‐MSUs, the symmetric cryptographic algorithm is used for communication between sub‐MSUs and slave stations that have limited computational resources. Our analysis shows that the HSKMA has the following distinctive advantages: 1) it supports the security requirement such as availability, forward security, and backward security, 2) it supports the required speed in the MODBUS implementation, and 3) it is suitable for the environments that have limited computational resources. Copyright © 2016 John Wiley & Sons, Ltd.

Modular exponentiation with a large modulus and exponent is a fundamental operation in many public-key cryptosystems. This operation is usually accomplished by repeating modular multiplications. Montgomery modular multiplication has been widely used to relax the quotient determination. The carry-save adder has been employed to reduce the critical path. This paper presents and evaluates a new and efficient Montgomery modular multiplication architecture based on a new digit serial computation. The proposed architecture relaxes the high-radix partial multiplication to a binary multiplication. It also performs several multiplications of consecutive zero bits in one clock cycle instead of several clock cycles. Moreover, the right-to-left and left-to-right modular exponentiation architectures have been modified to use the proposed modular multiplication architecture as its structural unit. We provide the implementation results on a Xilinx Virtex 5 FPGA demonstrating that the total computation time and throughput rate of the proposed architectures outperform most results so far in the literatures.