[Bug 19803] "Fingerprint" is unclear

https://www.w3.org/Bugs/Public/show_bug.cgi?id=19803

--- Comment #6 from Jussi Kalliokoski <jussi.kalliokoski@gmail.com> ---
(In reply to comment #5)
> Resolved: keeping fingerprint, better describing matching. 
> https://dvcs.w3.org/hg/audio/rev/f572fe073d58

The current wording doesn't quite communicate what I was proposing at the
teleconf:

If the system detects (for example) two devices attached to the user's computer
with the exact same pool of data used to generate the fingerprint, the second
one's fingerprint generation would inject information (of the previous
attempted fingerprint not being unique) to theentropy pool, and a third device
would do the same, and so on, thus maintaining association unless the order of
the devices changes.

This, I think, is the best guess you can get at uniquely identifying a device,
and the user agent doesn't need to maintain or store any information about
devices the user has had. A possible implementation in JavaScript that would
catch the gist of that:

var devices = new Map()

function createFingerprintForDevice(device) {
  var fingerprint
  var poolExtra = ''

  do {
    fingerprint = createUUID(device.entropyPool + poolExtra)
    poolExtra += '#existed'
  } while (devices.has(fingerprint))

  devices.set(fingerprint, device)

  return fingerprint
}

Not sure how to word this in the spec. Would it be worth dictating this,
regardless of how good the implementation is at producing unique fingerprints?

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Received on Friday, 7 December 2012 20:19:50 UTC