Change Address Detection in Bitcoin using Hierarchical Clustering

The widespread adoption and success of blockchain, particularly Bitcoin, was influenced by the promise of decentralization and anonymity. Sadly, these same characteristics have made it attractive to illegal activities, requiring careful oversight and targeted interventions. In order to mitigate illicit usage of this technology, we need to analyze and de-anonymize transactions occurring in the blockchain. For that purpose, change addresses identification is a promising technique, since change addresses can be associated to the inputs of the same transaction since they are meant to hold leftover funds for the same user. In this article, we propose a new approach of change address detection using hierarchical clustering. First, we developed a new method for data extraction of connected transactions. After collecting the transaction, we combined multiple input heuristics with a hierarchical clustering algorithm at the transaction level to study similarities in usage patterns between inputs and outputs. After applying our detection model, we analyze the generating cluster and evaluate the performance of our solution in terms of F1-score, result accuracy, recall and precision.