Browsers provide all sorts of details to websites that request them. There's the well-known "user agent string" that specifies the browser and computing platform being used, of course, but my own user agent string was not particularly unique. Much more incriminating were the details of my particular browser plugins (only 1 in 20,830 browsers have an identical plugin load) and the list of my system fonts (1 in 13,886).
Thursday, January 28, 2010
Ars Technica has a piece on EFF's Panopticlick project, looking at browswer 'fingerprints' as a tool for online tracking, even with cookies disabled and a dynamic IP address: