On Mon, Mar 10, 2014 at 1:14 AM, Tom Ritter <[email protected]> wrote: > As promised, here's a first-pass at a proposal: > https://github.com/tomrittervg/crypto-usability-study
Nice, comments - Fingerprint Types - Visual and poetry fingerprints seem worth including. Comparison Method - Business cards can only fit a small amount of text (since most of the space is taken up with other stuff), and don't typically contain high-resolution images. So I'm not sure that comparing things between screens can be reduced to comparing things on business cards. Approaches - I suggest giving users X seconds to perform a comparison between a pair of values that are either identical or close, then seeing whether they correctly distinguish these cases. X can be calibrated by performing some preliminary tests, then choosing a number that's likely to produce a variable error rate (i.e. not so low that subjects are always guessing randomly, not so high that they're always getting it right). This is modeled after "character legibility" studies, e.g. http://psychology.wichita.edu/surl/usabilitynews/81/legibility.asp - I don't see a reason to fake-out the user by having her perform extraneous tasks. Just seems like it would slow things down. Modulating Speed - For the "Spoken Aloud" test, why not just have pairs of subjects compare the fingerprints by speaking to each other? Error Rates - I'm not sure about the '"One Subtle Flaw" case, because the fingerprints have different notions of "tokens" so this will be hard to compare between formats. Also, it doesn't model a realistic attacker. - For the computationally-chosen flaw, I think you should just assume an attacker that can consider 2^80 random candidate fingerprints, and choose the closest-matched fingerprint this attacker could find (but of course don't actually do 2^80 hashes, just set 80 bits of the fingerprint equal). Trevor
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