Evaluation of Proof of Work (POW) Blockchains Security Network on Selfish Mining

Bitcoin is one of the first implementations of cryptocurrency or digital currency. It uses has increased in recent years along with the increasing volume of online transactions that require digital currency A blockchain is a digital ledger that allows parties to transact without use of a central authority as a trusted intermediary. In blockchain, there are a number of consensus protocols proposed including Proof of Stake, Proof of Elapsed Time, but most of the existing blockchain utilizes the computed Proof of Work (PoW) mechanism. Transaction security is secured in Bitcoin by using blocks with a hash-based Proof of Work (PoW) mechanism. PoW is a functional protocol that validates every incoming data to overcome spam attacks and Distributed Denial of Service (DDoS) attacks. Blockchain technology can store historically decentralized transaction data where each connected computer will store exactly the same data. To be able to perform an optimal transaction process, it is necessary to evaluate performance of the POW blockchain and find out what influences the transaction process. In this study, we compare simulation result of different block size and block interval to Block Propagation Time, time setup, and Average upload/download with selfish mining attack using NS3. The experimental results show that the smaller the block interval and block size, the smaller the Block Propagation time. It means that faster transactions are confirmed to peers on the network, and this affects the upload/download speeds.