# A Lightweight Hash-Based Blockchain Architecture for Industrial IoT
## 3 Proposed Lightweight Hash Based Blockchain Architecture for IIoT
### Network Interaction Process
To reduce the burden of broadcasting, we composed the cell nodes, which are nearby located to field devices and control devices. In the proposed architecture, each cell node gathers the transactions from the adjacent field devices, control devices. Also, it processes the mining process, and then broadcasts the block to other cell nodes participating in the blockchain. ## 5 Conclusions

In this paper, we proposed blockchain architecture that can change the hash function of blockchain flexibly according to the amount of transactions improving the availability of the blockchain network. In this architecture, we selected three lightweight hash functions (QUARK, PHOTON, and SPONGENT), which show better performance in perspective of implementing area, throughput, and power consumption. These hash functions can ensure cryptographic security and be implemented using small area (under 5000 GEs) for resource-constrained devices. Then, using these hash functions, we connected each data block by flexible hashchain. This approach can reduce the computational burden and latency. Also, we separated the field to some cells and composed the cell nodes to control each cell. This approach can improve the scalability of the network. In our simulation results, we revealed that the proposed architecture is suitable for an environment that should be processed within certain times, especially monitoring and supervision field among IIoT applications. Additionally, if the hash functions are implemented parallel or more lightweight hash functions are developed, we argue that the proposed architecture can be applied more various IIoT applications, which require the latency under 1 s. However, there are many IIoT applications that require the restricted latency (less than 500 ms), such as closed-loop control field, interlocking, and control field. In these cases, it seems that the availability still remains the main concern when blockchain technology is applied. In our future work, to demonstrate the performance of our proposed architecture on various IIoT applications, we plan to conduct a simulation using NS-3 simulator that can simulate similarly to the real environment. Furthermore, we will implement our proposed architecture in actual devices for analyzing performance and security against existing blockchain attacks and ICS attacks. Conceptualization, B.S. ; methodology, B.S. and J.P.; investigation, J.P.; writing--original draft preparation, B.S. ; project administration, J.H.P. ; funding acquisition, J.H.P. This study was supported by the Advanced Research Project funded by the SeoulTech (Seoul National University of Science and Technology). The authors declare no conflicts of interest. ## References

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