In this paper, we propose an online security-aware hardware scheduler, the so-called Secure And Fast hardware Scheduler (SAFAS), for real-time task scheduling in multi-core systems in the presence of schedule-based side-channel attacks. To avoid such attacks and ensure that all tasks meet their deadlines, SAFAS schedules critical tasks and their replicas using a hardware-based strict Least Slack Time first (LST) algorithm independently while it independently schedules the non-critical tasks using a hardware-based EDF algorithm. SAFAS enhances the system performance and reduces the chance of side-channel attacks due to the different processing cores allocated to each task in each scheduling interval. The hardware scheduler operates independently and in parallel with the multi-core system and hides the scheduling characteristics from adversaries. The software-based Earliest Deadline First (EDF) algorithm is also used for schedulability tests and feasibility analysis of hard real-time periodic tasks to maximize the number of tasks scheduled successfully in the multi-core system. SAFAS has been synthesized and simulated on a Xilinx Vivado 2018.2 and implemented on a Spartan-7 FPGA chip. Our experimental results indicate that SAFAS increases the performance of the system by 4.8 times as compared to previous state-of-the-art hardware schedulers while guaranteeing that all critical tasks and their replicas meet their deadlines. © 2022 Elsevier B.V.