To continue reading this article, please exit incognito mode or log in. Visitors are allowed 3 free articles per month without a subscriptionand private browsing prevents us from counting how many stories you've read. We hope you understand, and consider subscribing for unlimited online access. The digital currency Bitcoin has a reputation for providing privacy.
But a new analysis of the public log of all bitcoin transactions suggests it could be surprisingly easy for a law enforcement agency to identify many users of the currency. Popular uses for bitcoins include illicit gambling and making purchases at an online marketplace called Silk Road, where illegal drugs are traded openly. Inthe U. Her analysis centered on the digital trail left by bitcoin transactions, a mechanism used to provide trust in a currency that lacks the backing of a government or any other authority.
However, Meiklejohn and colleagues created maps from that record that could help law enforcement find companies that hold identifying information for specific users. An agency might, for example, follow the flow of bitcoins from an illegal transaction to a bitcoin exchange and then subpoena that company.
It is difficult to invest much in bitcoin or realize gains made in the bitcoin economy, lawful or otherwise, without using an exchange. Mt Gox requires a copy of government-issued photo ID and proof of address before a person can convert between conventional currencies and bitcoins. Meiklejohn says she has discussed her research with representatives of one U. A paper on the work will be presented at the Internet Measurement Conference in Barcelona next month.
The researchers used two techniques to unravel the thicket of 12 million addresses and 16 million transactions in the blockchain, covering the movements of about four million bitcoins. First, a network map of all the addresses was made based on the transactions between them.
Addresses clustered into tight groups suggested they belong to individual people or organizations. That map was then enhanced by labeling addresses linked to known people or services. Some of the information needed to do that came from looking online for people or companies who had publicly shared their bitcoin addresses. The researchers also did business with nearly different bitcoin companies and services to identify more addresses, buying a pile of goods from coffee to a Guy Fawkes mask.
The UCSD analysis suggests some easy places for law enforcement to start should they want to chase people using bitcoins for illegal transactions. For example, the researchers logged many transactions directly between Mt Gox and Silk Road, the marketplace where illegal drugs and other services are traded. That means a subpoena served on Mt Gox could immediately identify many people that had made use of Silk Road.
However, the services that exist are unreliable. They may never be able to launder large sums because hiding a large amount of cash, like the haul from a malware heist, would require having several similarly large amounts to mix them with.
Miers believes the UCSD group is the first to show the power of the approach used. Many in the Bitcoin community remain unaware of the potential for such attacks, says Miers. Almost a year later, most of the stolen coins have gone nowhere, suggesting that the person who took them is struggling to cash out without revealing himself, says Meiklejohn.
Catch up with our coverage of the event. AI startup Gamalon developed a clever new way for chatbots and virtual assistants to converse with us.
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