Bitcoin is a peer-to-peer electronic cash system that maintains a public ledger with all transactions. The public availability of this information has implications for the privacy of the users. The public ledger consists of transactions that transfer funds from a set of inputs to a set of output addresses. As long as those addresses cannot be linked to their owners, privacy is preserved. The linking of addresses to owners results in privacy leaks. The possibilities of linking addresses to owners are multiplied when addresses are used to receive funds more than once. In this work we describe privacy-leaking effects of address reuse and gather statistics of address reuse in the Bitcoin network.

We also describe collaborative (CoinJoin) transactions that prevent the privacy attacks that have been published in the literature. Then we analyze the Blockchain to find transactions that could potentially be CoinJoin transactions.

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