Mixers Detection in bitcoin network: a step towards detecting money laundering in crypto-currencies

Anonymity is one of major factors that is causing the rise of bitcoin crypto-currency. There are several attacks (positive or negative) to de-anonymize the bitcoin addresses, in order to link the bitcoin entity to a physical entity or person. Bitcoin mixing service (called mixer) is one of the approaches to keep the user’s crpto-anonymity in the transparent ledger of bitcoin network. Mixers breaks the link between the sender and the receiver by mixing up coins received from multiple sources, while creating a mess to make it impossible to identify the actual sender of bitcoins. On the other hand, mixing services are being vastly exploited by criminals for laundering the illegal money, taken from frauds, ransom, scams, or other illegal activities. Detecting mixing services or mixer’s involvement in a transaction can help in discovering money laundering activities in the bitcoin blockchain. Existing mixer’s detection approaches either have a low accuracy-rate due to the changing nature of the mixing process or they are not efficient enough to be implemented in a real-time environment. In this paper, we developed a highly accurate decision-tree based model using C4.5 machine learning approach to identify addresses providing mixing services. To make this detection process efficient and be able to work in a real environment, we reduced overall feature-set to only eight features, minimizing overall computation time. Further, we shrink the decision-tree using reduced error-pruning to make the detection process faster. With the short decision-tree-size of 55 nodes, we achieved the accuracy of more than 97%, which is quite higher.