Bitcoin - Accepting Merchants' Cookies Threaten User Anonymity
Researchers from Princeton University have released their findings on how online ad trackers can impact the privacy of cryptocurrency transactions. The title of the new research paper is, "When the cookie meets the blockchain: Privacy risks of web payments via cryptocurrencies." The privacy issues happened on more than 100 online merchants from over 20 countries that accepted cryptocurrencies. Cookies and other information received/got by ad trackers that are used on e-commerce places can show/tell about the identity of customers who pay with cryptocurrencies. Some of the information online stores share with third party advertisers can purchases a user has made, how much they have spent, as well as contact and shipping information. Even for online stores which do not collect much information about, users could obtain incriminating information if a user purchases a product with a cryptocurrency and then later purchases a product from the site using a credit card.
Some of the larger online vendors which accept cryptocurrencies include Overstock, Newegg, and Microsoft, all of which use third party ad trackers. Google's ad tracker is said to be on nearly 80% of the internet, according to the researchers from Princeton. Some of the major ad trackers, such as Google and Facebook, also get information directly from user accounts on their services, but most ad trackers do not have that advantage.