Web Browsers Leave 'Fingerprints' Behind as You Surf the Net
Abstract. We investigate the degree to which modern web browsers are subject to \device fingerprinting" via the version and configura-tion information that they will transmit to websites upon request. We implemented one possible fingerprinting algorithm, and collected these fingerprints from a large sample of browsers that visited our test side,panopticlick.eff.org. We observe that the distribution of our fnger-print contains at least 18.1 bits of entropy, meaning that if we pick a browser at random, at best we expect that only one in 286,777 other browsers will share its fingerprint. Among browsers that support Flash or Java, the situation is worse, with the average browser carrying at least 18.8 bits of identifying information. 94.2% of browsers with Flash or Java were unique in our sample.