Unraveling blockchain based crypto-currency system supporting oblivious transactions: A formalized approach

Lin Chen, Lei Xu, Nolan Shah, Nour Diallo, Zhimin Gao, Yang Lu, Weidong Shi

Research output: Chapter in Book/Report/Conference proceedingConference contribution

4 Scopus citations

Abstract

User privacy is an important issue in a blockchain based transaction system. Bitcoin, being one of the most widely used blockchain based transaction system, fails to provide enough protection on users' privacy. Many subsequent studies focus on establishing a system that hides the linkage between the identities (pseudonyms) of users and the transactions they carry out in order to provide a high level of anonymity. Examples include Zerocoin, Zerocash and so on. It thus becomes an interesting question whether such new transaction systems do provide enough protection on users' privacy. In this paper, we propose a novel and effective approach for de-anonymizing these transaction systems by leveraging information in the system that is not directly related, including the number of transactions made by each identity and time stamp of sending and receiving. Combining probability studies with optimization tools, we establish a model which allows us to determine, among all possible ways of linking between transactions and identities, the one that is most likely to be true. Subsequent transaction graph analysis could then be carried out, leading to the de-anonymization of the system. To solve the model, we provide exact algorithms based on mixed integer linear programming. Our research also establishes interesting relationships between the de-anonymization problem and other problems studied in the literature of theoretical computer science, e.g., the graph matching problem and scheduling problem.

Original languageEnglish
Title of host publicationBCC 2017 - Proceedings of the ACM Workshop on Blockchain, Cryptocurrencies and Contracts, co-located with ASIA CCS 2017
PublisherAssociation for Computing Machinery, Inc
Pages23-28
Number of pages6
ISBN (Electronic)9781450349741
DOIs
StatePublished - Apr 2 2017
Event1st ACM Workshop on Blockchain, Cryptocurrencies and Contracts, BCC 2017 - Abu Dhabi, United Arab Emirates
Duration: Apr 2 2017 → …

Publication series

NameBCC 2017 - Proceedings of the ACM Workshop on Blockchain, Cryptocurrencies and Contracts, co-located with ASIA CCS 2017

Conference

Conference1st ACM Workshop on Blockchain, Cryptocurrencies and Contracts, BCC 2017
CountryUnited Arab Emirates
CityAbu Dhabi
Period04/2/17 → …

Keywords

  • Anonymization
  • Blockchain
  • Privacy

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  • Cite this

    Chen, L., Xu, L., Shah, N., Diallo, N., Gao, Z., Lu, Y., & Shi, W. (2017). Unraveling blockchain based crypto-currency system supporting oblivious transactions: A formalized approach. In BCC 2017 - Proceedings of the ACM Workshop on Blockchain, Cryptocurrencies and Contracts, co-located with ASIA CCS 2017 (pp. 23-28). (BCC 2017 - Proceedings of the ACM Workshop on Blockchain, Cryptocurrencies and Contracts, co-located with ASIA CCS 2017). Association for Computing Machinery, Inc. https://doi.org/10.1145/3055518.3055528