# The Modification of pBFT Algorithm to Increase Network Operations Efficiency in Private Blockchains
## 1 Introduction  
Blockchain is a decentralized data ledger management-based technology that allows direct transactions between users through the sharing and management of all transactions by all nodes connected to the decentralized network environment [1]. Through a hash function-based encryption and encryption through electronic signatures, the blockchain actively applies security technology and enables data protection and precise management based on decentralization [2]. Comprehensive technology applications are increasing, such as in inventory tracking, origin certification, and financial services, and the global financial consulting enterprise PricewatenthouseCoopers (Pwc) has predicted that most global businesses will adopt blockchain, and that blockchain will boost global GDP by USD 1.76 trillion by 2030, setting the economic value of blockchain at USD 7600 by this time [3]. As per the increase in contact-free environments and development of communications, the amount of data being transacted and handled is increasing. In most cases, the data managed by an organization are transacted and handled by a third party or a centralized management form. With the size and range of data created by organizations and websites becoming larger every day, and companies seeking to utilize the value of said data, many are seeking to supplement the data breach dangers associated with the centralized management form and are looking for a new value of data application [4, 5]. Blockchain is widely applied not only to government agencies but also to the Industrial Internet of Things (IIoT) and, recently, research in which blocks are arbitrarily compressed without considering latency for an optimized solution of IIot is being conducted [4]. Since the blockchain is composed of many nodes, there is a possibility that a malicious attack may occur, which may lead to the Byzantine general problem. Various consensus algorithms suggest a way to solve the Byzantine general problem, but most are processed based on a synchronous system. pBFT is one of the blockchain consensus algorithms thatcan solve the Byzantine general problem in an asynchronous network and guarantee the finality of the consensus. The pBFT consensus algorithm has the advantage in that it can normally lead to a consensus even with the malicious behavior of less than 33% of nodes, but since it is premised that communication between all nodes is required for consensus, the network operation cost increases as the number of nodes increases. Variants of pBFT include Tendermint and Neo, and EdgeTC (electronic toll collection) is an example of using pBFT on an inter-institutional blockchain platform [6]. Tendermint and Neo increase the speed and efficiency by applying the delegated method. Recently, as the application of blockchain by government agencies increases, a modified blockchain consensus algorithm that can increase economic efficiency and availability by considering the characteristics according to the weight of work is needed. In the case of government agencies, since the weight of the client's request is varied, it is necessary to further subdivide and transform the contents of the consensus algorithm such as Tendermint. This paper proposes a modified pBFT (mpBFT) as a method to flexibly process the consensus algorithm in consideration of the weight of tasks in a public blockchain composed of nodes based on trust, such as government agencies, and to efficiently manage network operation costs. The mpBFT proposed in the study of this paper is a trust-based consensus algorithm that can be used efficiently between organizations, and it simplifies the process and guarantees the stable selection of leader nodes. In this study, when a client requests a state change, a state flag that distinguishes the importance of Msg is requested together, and PreCommit is performed by the minimized leader nodes in the preparation and commit stages.