So this is the old E-tag trick? It's not new at all, but perhaps it hasn't been as widely published. This can also be done with the Date / If-Last-Modified header, manufacturing a cookie "date".
http://www.nikcub.com/posts/persistant-and-unblockable-cooki...
As an update to that post from 2011, I never did get the browsers to update their parsers.
This E-Tag bug has been known for over a decade. As part of my post I tried to find the earliest written record of it and found a post in 2003:
http://www.arctic.org/~dean/tracking-without-cookies.html
It seems to get 'rediscovered' at least a couple of times a year.
Another criticism "It has already being used by numerous websites but few people know of it" without any more information. If you know of which websites, you should state so, if you don't, you should at least say why you know "numerous websites" use it. Also the "few people know of it" bit, a bit presumptive if you were referring to the engineering community, and flatout meaningless if you were referring to everyday people, of which many don't even know what a browser is.
I did like the working example, but maybe tone down the hyperbole and more informative claims when the claims are also accusations.
> Your tone is definitely one pushing it as a new and ominous discovery.
I'm sorry if the tone gave a wrong impression, that wasn't my intention (English isn't my native language). It was quite a discovery to me though, perhaps that's why I made it sound like that without really meaning to.
> Another criticism "It has already being used by numerous websites but few people know of it" without any more information
Oh that's right! I had a source link elsewhere but forgot to move it when rearranging text. I'll add this again now.
> Also the "few people know of it" bit, a bit presumptive if you were referring to the engineering community
This was mostly my personal experience. I don't know anybody knowing about these etags being used for tracking, while I know that many friends and classmates could give me details on how cookies work or how localstorage works.
Edit: Why are people downvoting the person I replied to?
Two options:
* Someone's grumpy and/or a jerk and/or an idiot
* Someone's reading HN on a touch device, wanted to
upvote, touched the wrong icon.Can't find the HN story now, but it was a recurring story for a few days as people argued back and forth whether it was ethical.
Zalewski's "I know which sites you visit" asteroids clone is probably from the funkier end: http://lcamtuf.blogspot.fi/2013/05/some-harmless-old-fashion...