Cryptology ePrint Archive: Report 2012/596

Evaluating User Privacy in Bitcoin

Elli Androulaki and Ghassan Karame and Marc Roeschlin and Tobias Scherer and Srdjan Capkun

Abstract: Bitcoin is quickly emerging as a popular digital payment system. However, in spite of its reliance on pseudonyms, Bitcoin raises a number of privacy concerns due to the fact that all of the transactions that take place are publicly announced in the system.

In this paper, we investigate the privacy guarantees of Bitcoin in the setting where Bitcoin is used as a primary currency for the daily transactions of individuals. More specifically, we evaluate the privacy that is provided by Bitcoin (i) by analyzing the genuine Bitcoin system and (ii) through a simulator that mimics Bitcoin client’s behavior in the context where Bitcoin is used for all transactions within a university. In this setting, our results show that the profiles of almost 40% of the users can be, to a large extent, recovered even when users adopt privacy measures recommended by Bitcoin. To the best of our knowledge, this is the first work that comprehensively analyzes, and evaluates the privacy implications of Bitcoin. As a by-product, we have designed and implemented the first simulator of Bitcoin; our simulator can be used to model the interaction between Bitcoin users in generic settings.

Category / Keywords: Bitcoin, anonymity, privacy, behavioral clustering

Date: received 19 Oct 2012, last revised 6 Feb 2013

Contact author: elli androulaki at inf ethz ch

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Version: 20130206:103700 (All versions of this report)

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