EFF’s Panopticlick Pierces My Privacy Illusion


Ran this the other day in Firefox and got:

Your browser fingerprint appears to be unique among the 551,209 tested so far.

Currently, we estimate that your browser has a fingerprint that conveys at least 19.07 bits of identifying information.

Not one of the 551,209 browsers tested so far emit my plugin details

Similarly, not one of those 551,209 browsers has the same mix of fonts installed.

Might as well surf naked.

IE8 with privacy mode on is only a little better:

Within our dataset of several hundred thousand visitors, only one in 275,626 browsers have the same fingerprint as yours.

Currently, we estimate that your browser has a fingerprint that conveys 18.07 bits of identifying information.

And that 'other person' is probably … me.

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5 Responses to EFF’s Panopticlick Pierces My Privacy Illusion

  1. elliottg says:

    I don’t believe it. I think fingerprinting is a concern, but I don’t believe that they have tested that many unique browsers. I just hit it 3 times in a row. The number of tested browsers kept on going up and yet they kept on telling me I was unique without noting that I hit the test me button more than once. That is a priori evidence that their methodology is really, really flawed.

  2. Steve says:


    Remember, unless you’re a DHCP client, your IP address is absolutely unique.

    I don’t hear any black helicopters. . .

  3. michael says:

    I do have a dynamic IP number at home; changes every day or so.

  4. insecurity says:

    The EFF’s Peter Eckersley has posted several comments on the methodology over at Schneier’s blog.

    In addition, the first item in the Panopticlick FAQ also explains the use of session cookies to track some repeat visitors:

    Q: Why does your browser remain unique, even if you reload the page?

    A: As noted in the panopticlick privacy policy, the site uses a 3-month persistent cookie to try to prevent double-counting of browsers.



  5. Mike Marshall says:

    Loved this.

    Also loved the title of the site. As you may know, the Panopticon was a prison designed by Jeremy Bentham. In it, a elevated central observation tower sits in in the center of a circular prison. From it, the imprisoned may be observed by guards inside the tower, but the prisoners can never see the guards. Thus, there is a constant sense on the part of the imprisoned that they are being watched but they can never see who is watching.

    Foucault took this image to draw a metaphor for our own society- we are all imprisoned and observed by forces beyond our control and invisible to us.

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