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> I write webapps for a living.

I’d imagine most people in this thread do or have. Myself included. It’s a pretty massive industry :)

What you’re missing is that whatever you do to remove fingerprints does itself add a unique metric to fingerprint. This is also compounded by how easy, cheap and legal it is to add fingerprinting tech to ones site. Literally the only way to break fingerprinting is if the majority of the web browsing population ran systems that randomised fake responses. But as it stands at the moment, it’s possible to:

1. Identify when a plug-in it overloading a builtin function

2. Identify which users are consistently doing so because so few are and there’s methods of fingerprinting that exist outside of your JS VM.

I don’t have the link to hand but there’s a website that you can visit and it tells you how identifiable you are. I used to think it was possible to hide until I visited that site and then I realised just how many different metrics they collect and how a great many of them are literally impossible to block or rewrite without breaking the website entirely.



You may have been thinking of this one: https://coveryourtracks.eff.org/


It was this one: https://www.amiunique.org/fp

It goes into more detail than the EFF link where it breaks down your uniqueness per each metric (and how much entropy each metric adds) as well as giving you an overall uniqueness.

It's a fantastic but also scary resource :)


The cover your tracks implementation also breaks down uniqueness per category, per metric.

They are nice resources, but don't get too scared!

Frankly, both are exaggerating a little - e.g. including stuff like browser version numbers which only appear as unique as they do because the time-span they cover is long enough to overlap update cycles (AmIUnique even seems to have it cover the entire history by default??? That's just noise), yet not stable for more than a short period of time. AmIUnique includes the exact referer, which is likely not nearly as useful as that would make it seem.

Then there's stuff like "Upgrade Insecure Requests" and "Do not track", which is likely extremely highly correlated with browser version choice.

Both sites can't really tell you how reliable the identification is, only how unique you are at this moment. And that matters a lot, because if identification is unreliable (i.e. the same person in some metric has multiple distinct fingerprints) the end result is that for reliable overall identification a fingerprinter may need many times as many bits of entropy as a naive estimate might assume, especially if visits are occasionally sparse and thus changes to fingerprints may frequently come all at once.

Clearly over the very short term you are likely uniquely identifiable as a visitor. However, it's less clear how stable that is.




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