Uma proposta para aprimorar o anonimato em transações bitcoin com suporte à auditoria

Abstract

This work show an avaliation about the performance of the application of Group Signature technique in Bitcoin system and a study about the anonymity and auditory. The Bitcoin’ goal is provide a virtual currency and an anonymous online transaction system. However, recent researches show that can be to break the anonymity of transactions through the chronological traceability technique in the Bitcoin transactions and analysis of network addresses. As a result of breaking anonymity of Bitcoin transactions, users’ privacy and all Bitcoin ecosystem are affected negatively. For this reason, in this work, it was proposed to include Group Signatures techniques in the Bitcoin system to increasing of anonymity in Bitcoin transactions but with audity possibility in accept time, more or less 10 minutes. The Group Signature generate a lot of dinstinct groups to dinstinct Bitcoin transactions. After to include the Group Signature technique in a modified version of Bitcoin system, we evaluated this technique in Bitcoin system through experiment in simulations. Through the experiments and statistic analysis, it was found that the approach of including the Group Signature is feasible for implementation in Bitcoin system with small groups, 500 clients. For the all cases analyzed, it was verified that the use of Group Signature in Bitcoin transactions increase the anonymity. Therefore, it was verified that the performance of Bitcoin transactions with Group Signature technique show a delay in nearly 50% less than current Bitcoin system whitout this technique. Nevertheless, in small groups with Group Signature get a better anonymity level and audity, but in big groups with more than 500 clients this technique not is good because the transactions time is over.