Evercookie

Evercookie (also known as supercookie[1]) is an open-source JavaScript application programming interface (API) that identifies and reproduces intentionally deleted cookies on the clients' browser storage.

[4] In 2013, Edward Snowden leaked a top-secret NSA document that showed Evercookie can track Tor (anonymity networks) users.

[1][6] Further research on fingerprinting and search engines also draws inspiration from Evercookie's ability to track a user persistently.

[9] Due to privacy concerns, all major browsers include mechanisms for deleting and/or refusing cookies from websites.

In 2014, a research team at the Princeton University conducted a large scale study of three persistent tracking tools: Evercookie, canvas fingerprinting, and cookie syncing.

The team crawled and analyzed the top 100,000 Alexa websites, and detected a new storage vector, IndexedDB, that is incorporated into an Evercookie mechanism and used by weibo.com.

The authors proposed that searchers’ identity and user preference have a strong indication on the queries meaning and can greatly reduce the ambiguity of the search word.

[4] On Friday July 29, 2011, a research team at the University of California, Berkeley crawled the top 100 U.S. websites based upon QuantCast.

[26] KISSMetrics revised its privacy policies during the weekend, indicating the company had fully respected customers' will if they chose not to be tracked.

[27][28] In 2013, an internal National Security Agency (NSA)'s presentation was revealed by Edward Snowden, suggesting Evercookie's use in government surveillance to track Tor users.

[30][31] Evercookie, and many other emerged new technologies in persistent data tracking, is a response to internet users' tendency of deleting cookie storage.

[33] A Wall Street Journal survey showed 72% felt offended when they saw targeted advertisements while browsing the internet.

Another survey showed 66% of Americans felt negative about how marketers track their data to generate individualized information.