Financial and lives lost are possible consequences when disruption of an electricity supply occurs, due to security breaching of an industrial control system (ICS). Enhancing security of a geographical-wide ICS such as supervisory control and data acquisition (SCADA) system will require considerable efforts and capital. In addition to cost, system time sensitivity is also a major issue when one wants to implement security schemes at the existing SCADA. In addition to introduction on the need to secure SCADA, this paper is to focus on encryption for SCADA that are already in operation. Selecting a lightweight cipher such as lightweight encryption devices (LED) with its mathematical algorithms that suits hardware implementation, allows a complete cipher system to be hosted on a single low-cost FPGA, while satisfying time-latency of encrypting/decrypting of SCADA data packets. Though LED has no key scheduling and small key length, its security level is comparable to that of 256-bit Advanced Encryption Standard (256-AES), the current security adopted standard. Hardware architectures of LED for encrypting transmitted data are explored with insights on implementation of Galois multiplication into FPGA. In addition to provide a bump-in wire encryption, the proposed approach can be applied for Internet of Things (IoT).