Syllabus Lesson 20 of 156 · Fingerprinting: tracking without cookies
Fingerprinting: tracking without cookies

Quiz

Why it matters Being able to say which traits give away the most is what lets you judge any privacy tool or test site for yourself.

Time to check what you now know about fingerprinting. A quick reminder before you start:

  • A fingerprint is recomputed from your device on every visit, so clearing cookies does not reset it.
  • Each trait gives a number of bits: the rarer it is, the more bits. About 33 independent bits could single out one person.
  • Related traits must not be counted twice, and "unique" always means unique within some crowd.
  • Defences either make everyone look the same (uniformity) or make each site see something different (randomisation).
  • GPC is a clear request not to sell or share your data, not a blocker.

Several questions ask you to rank traits. Think "how many people share this?" A trait shared by almost everyone gives away little; a trait shared by very few gives away a lot.

Recap

  • Rarer trait -> more bits -> more identifying.
  • Combinations matter more than any single trait.
  • Pick defences that keep you in a big crowd or change what each site sees.

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