An Adaptive Random Walk Algorithm for Selecting Tips in the Tangle

Number of devices using Internet is increasing every day and this fact makes the need to improve the Internet of things protocol more than ever. Data protection and privacy is one of the key challenges in the Internet of Things technology. Dangers involved in the centralized technology of Blockchain system have led to the idea of using Tangle, which is a decentralized system. The main purpose of this new technology is to improve the problems and limitations of Blockchain such as high cost and time to confirm a transaction. In this new architecture, every node is involved in maintaining network security. This way, if a transaction is created, then it should select and confirm two unconfirmed transactions issued before. A walking algorithm is needed for this selection. Walking algorithms presented in literature thus far are either weighted or unweighted. An unweighted random walk algorithm can approve transactions nearly proportional to the time of their arrivals while a weighted algorithm can better defend against lazy and malicious transactions. In this paper, a new random walk algorithm is presented that has the benefits of both algorithms at the same time. The idea is to adapt the weight value to the current situation of transactions. Numerical results have shown the superiority of the proposed algorithm in comparison to the existing algorithms in providing a balance between timeliness of approving transactions and protecting against malicious activities.