## 6 Discussion and Conclusions  
In the future, with the increasing prevalence of NB-IoT and 6G networks, a multitude of IoT devices will be directly connected to the Internet using these technologies. These devices may not fall under the conventional internal network's control, giving rise to a new set of information security challenges. Consequently, this study's primary innovations and contributions can be summarized as follows:  
* This paper introduces an FPGA-based implementation of a zero-trust secure stream data transmission system. It is designed for the transmission of inter-endpoint streaming signals, aligning with the fundamental principles of zero-trust networks. * To prevent eavesdropping on transmitted information, this paper innovatively combines the principles of one-time passwords and one-time pads, creating the operational flow known as the One-Time Password Pad Process (OTP\({}^{3}\)) for secure transmissions between paired IoT devices. * To tackle the substantial computational burden on the micro-processor, this paper introduces a mechanism in processing key block generations, non-repeating checks, and data block transfers for the stream pipeline and hardware accelerators. * This hardware-accelerated and software co-designed approach effectively alleviates the workload on the micro-processor, thereby enhancing the overall system performance. Experimental results demonstrate remarkable throughput performance enhancements compared to traditional design schemes. By harnessing the distinctive transmission characteristics and specific environments of IoT, such as the uninterrupted streaming signal exchange between devices and the preset two devices as a communication pair, this paper introduces OTP\({}^{3}\). It is a secure mechanism tailored for transmitting streaming signals between IoT device endpoints within the zero-trust network framework. The implementation is carried out on an FPGA, incorporating hardware processing modules that facilitate real-time data stream pipeline processing. Empirical results affirm its efficiency in encryption processes and its capacity to handle substantial volumes of transmitted data within the data-plane of the Fog Computing architecture. Furthermore, the FPGA designs implemented in this system can be translated into an Application-Specific Integrated Circuit (ASIC), resulting in reduced production costs and lower power consumption for large-scale manufacturing. This represents a significant advantage for IoT devices, compared to methods employing Graphics Processing Units (GPUs), which are also utilized for accelerating data processing. Designing the proposed OTP\({}^{3}\) operation flow with related functional components using both ASIC and GPU approaches necessitates substantial engineering effort. However, it is worthwhile undertaking this task, as conducting a more comprehensive comparison will be instrumental in validating the performance of the proposed solution, contributing to the next phase of advanced progress in this research. Another future endeavor involves a collaborative design with a Quantum Key Distribution (QKD) key exchange method [56], like the pioneering BB84 QKD protocol [57]. This approach allows two parties to establish a shared encryption key through a quantum channel, known as a QKD link [58]. In the event of an eavesdropper's attempt to intercept the key, quantum principles will enable the communicators to detect such intrusion. QKD offers a solution to the security challenges posed by the Diffie-Hellman (DH) algorithm [48], used for public key exchange on the Internet, particularly in anticipation of future threats, including those associated with Quantum Computing. Therefore, further empirical validations in real-world scenarios, particularly under diverse and challenging conditions, are worth pursuing as future works with respect to this paper. This work is supported by the NSTC, ROC, under grant number of NSTC 112-2637-E-025-003. **Institutional Review Board Statement:** Not applicable. **Informed Consent Statement:** Not applicable.