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What's the point of ubercookie?

Think of it as a modern version of Samy Kamkar's evercookie:
"evercookie [...] produces extremely persistent cookies in a browser. Its goal is to identify a client even after they've removed standard cookies, Flash cookies, and others."

The only difference is, that ubercookie doesn't need to store any data to identify you. It just does some fancy computations in your browser and the results are unique to the details of your personal setup.

The point of ubercookie is to demonstrate the impact of two fingerprinting techniques discovered recently, to raise awareness for these issues, and to push the browser vendors to fix them.

How does it work?

Ubercookie uses two Javascript-APIs to create a fingerprint of your hardware, OS, and browser engine:

Does it work X-Domains?

Yes, x-domain tracking is easy because the fingerprinting is completely independent of the Same-origin policy.

Does it work X-Browsers?

It depends. As long as the two browsers are based on the same engine it works. On iOS it works between all browsers, on desktop between Chrome and Opera, and even between Firefox and the Tor Browser.
Additionally the fingerprints seem to be mostly persistant between different versions of a browser on a certain system.

How unique is my fingerprint?

I'm not quite sure. The methods used create very unique results for different hardware, but it's hard to say how unique those fingerprints are for devices with identical setups. There is not enough data yet. Though fingerprints were all unique among ~50 almost identical devices I tested by hand and with Browser Stack.
Even if the fingerprints wouldn't be perfectly unique, they'd still provide a huge diversity and stability.

How can I protect myself?

Currently the only way to really protect yourself from getting tracked by this techniques is to use NoScript. Hopefully the browser vendors will come up with a better solution soon.

Do you track me?

Nope. Ubercookie doesn't store any data. Everything stays on your device.

How can I support the project?

Further Resources