More and more shopping Web sites accept cryptocurrencies as a method of payment, but users should be aware that these transactions can be used to deanonymize them – even if they are using blockchain anonymity techniques such as CoinJoin.

Independent researcher Dillon Reisman and Steven Goldfeder, Harry Kalodner and Arvind Narayanan from Princeton University have demonstrated that third-party online tracking provides enough information to identify a transaction on the blockchain, link it to the user's cookie and, ultimately, to the user's real identity.

"Based on tracking cookies, the transaction can be linked to the user's activities across the web. And based on well-known Bitcoin address clustering techniques, it can be linked to their other Bitcoin transactions," they noted.

Add to this the fact that many merchants additionally leak users' PII such as name or email address to trackers, and if becomes obvious that trackers can easily link the transaction to a user's web profile and identity.

But, until know, it was possible to believe that using mixing technique such as the aforementioned CoinJoin or other types of coin mixing would prevent the linkage of Bitcoin addresses to user's identity. Unfortunately, that's not true.