Bitcoin anonymity a peer-to-peer electronic currency system is a complicated issue. Within the system, users are identified by public-keys only. An attacker wishing to de-anonymise its users will attempt to construct the one-to-many mapping between users and public-keys and associate information external to the system with the users. Bitcoin tries to prevent this attack by storing the mapping of a user to his or her public-keys on that user’s node only and by allowing each user to generate as many public-keys as required.

In this research, the authors consider the topological structure of two networks derived from Bitcoin’s public transaction history. The authors show that the two networks have a non-trivial topological structure, provide complementary views of the Bitcoin system and have implications for anonymity. They combine these structures with external information and techniques such as context discovery and flow analysis to investigate an alleged theft of Bitcoins, which, at the time of the theft, had a market value of approximately half a million U.S. dollars.

Bitcoin is a peer-to-peer electronic currency system first described in a paper by Satoshi Nakamoto (a pseudonym) in 2008. It relies on digital signatures to prove ownership and public history of transactions to prevent double-spending. The history of transactions is shared using a peer-to-peer network and is agreed upon using a proof-of-work system.

Many users adopt Bitcoin for political and philosophical reasons, as much as pragmatic ones. There is an understanding amongst Bitcoin’s more technical users that anonymity is not a prominent design goal of the system; however, opinions vary widely as to how anonymous the system is, in practice. Jeff Garzik, a member of Bitcoin’s development team, is quoted as saying it would be unwise “to attempt major illicit transactions with Bitcoin, given existing statistical analysis techniques deployed in the field by law enforcement” however, prior to this work, no analysis of anonymity in Bitcoin was publicly available to substantiate or refute these claims.

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