Making Bitcoin Less Anonymous?

The creator of Bitcoin, Satoshi Nakamoto, highlighted an inherent weakness in the bitcoin protocol in his published paper Bitcoin: A Peer-to-Peer Electronic Cash System. He highlighted that even though new key pairs should be used for a new transaction to keep them from being linked to a common owner, “… some linking is still unavoidable with multi-input transactions, which necessarily reveal that their inputs were owned by the same owner. The risk is that if the owner of a key is revealed, linking could reveal other transactions that belongs to the same owner.” This is quite prevalent in the economy today, from public donation addresses being posted everywhere on the Bitcoin forums to Wikileak’s own website.

By properly modeling the Bitcoin blockchain and grouping these multi-input (and multi-output!) transactions into entities, a single identified address could reveal large pools of addresses. Combined with the thousands of addresses attributed to people’s signatures on the Bitcoin forums, or even privileged market data from Mt. Gox, we believe portions of the economy could be identified. Even if an entity was not explicitly marked, its relationships with other entities may reveal its associations, thus implicitly identifying them.

Nonetheless, we will still generate a highly visual model of the blockchain and perform analysis on that with tools such as https://gephi.org/, something that simply has not happened yet. Special permission was given to me from blockchain.info which allows me to hit their API unthrottled, so expect to see some cool stuff in the future!