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Uniqueness of fingerprints?

Uniqueness of fingerprints?

Posted Apr 3, 2008 10:56 UTC (Thu) by filipjoelsson (guest, #2622)
In reply to: Uniqueness of fingerprints? by espeer
Parent article: Biometrics for identification

Doesn't matter. One fingerprint does not correlate with one valid image anyway, and not with
two either. I don't know what the correlation is, but I would bet on thousands of valid images
per fingerprint.

The problem is that a fingerprint isn't even presumed to be unique for every living human
(Wikipedia has three examples of false positives, from Europe and the US from 1997 to date,
that is clearly a limited population, time and fingerprint database). And while the
fingerprint has molecular resolution, an image of one hasn't - so uniqueness definitely drops
quit a bit. So instead of one in 100 million, you may very well drop to one in 100 thousand.

The pigeon hole principle certainly applies.

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Uniqueness of fingerprints?

Posted Apr 4, 2008 2:16 UTC (Fri) by kevinbsmith (guest, #4778) [Link]

I went to wikipedia, hoping to read a cool article describing three pairs of people with
identical fingerprints. Boy was I disappointed.

This wikipedia article ( lists several cases where
fingerprint evidence was misleading, but none of them were likely due to two people actually
having the same fingerprint. One was a blatant clerical error, and one was simply shoddy
police work. In a third case, DNA evidence freed the suspect, and later investigations
concluded the police had misidentified the fingerprint.

The final case had a police officer's fingerprints found at a crime scene where she claimed
not to have been. Early fingerprint experts were of mixed opinions, but later examiners were
overwhelmingly convinced that the fingerprint was not hers. The image may have been ambiguous
and/or there may have been manipulation of the evidence.

So while I'm not a fan of biometrics, and I don't have absolute faith in fingerprints, this
particular article doesn't provide proof that there have been collisions. 

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