At 02:41 PM 4/19/00 -0400, ericm wrote: >> A finger can change, so perhaps the key can be encrypted with multiple >> "near matches" and those copies also stored. > A fingerprint is 20 points in 2-D, apparently with 16 bits of resolution. This is a 40-dimensional space with 16 bits of resolution, nominally. Tolerance for geometric transforms (e.g., rotation) reduces this. Each identity is a point in this space; each measurement is too. Measuring the distance between them is well understood, as is the signal-detection theory behind the decision-making (thresholding) that follows. Its a little more complicated when you can toss out points. Remember that recognition is easier than recall ---you should tell the system who you claim to be, don't make it guess. (And as others have reminded, tell it something only you know also.) A print should match (or not) an identity, that ident has a truly random key associated with it. A print makes a poor key, minutiae are not random.
