Mapping user behaviors to identify professional accounts in Ethereum using semi-supervised learning

Ethereum is one of the largest blockchain platforms currently that has become a digital business environment. This platform allows for decentralized transactions between anonymous users. Thus, the development of methods to identify users' behaviors and keep them anonymous can potentially leverage business on this platform. In this work, we aim to combine different categories of machine learning approaches, namely, unsupervised and semi-supervised, to map the behaviors of users' owned accounts and identify users with professional activities in Ethereum. In addition, we provide here data to the community and analyze different machine learning techniques to characterize the users of Ethereum. These are challenging tasks due to the small fraction of publicly labeled data referring to users' accounts that provide services on this platform, such as exchange, payment, and entertainment, among most casual behavior users. Initially, we use unsupervised learning techniques to cluster the unlabeled users' accounts and to identify a set of them with casual behavior. As an outcome, a dataset containing labeled (casual or professional) and unlabeled instances is obtained. Semi-supervised learning methods are then applied (i) to generate models that classify accounts' behaviors into casual or professional ones and (ii) to discover accounts with professional behaviors among the unlabeled ones. Computational experiments were conducted, and the results obtained by the proposed procedure are compared to those achieved by supervised learning techniques from the literature. The proposal outperformed those from the literature and reached values higher than 95% for the accuracy, precision, recall, F beta-scores, MCC, and AUC-ROC.