Richard Clayton <richard(_at_)highwayman(_dot_)com> wrote:
Goodman & Rounthwaite have an interesting paper on using Captchas to
limit webmail usage (one conclusion is that you need quite a number of
them). It was presented at EC'04 yesterday, but the link on Joshua's
home page is not currently working -- I expect he'll fix it when he gets
home :(
http://research.microsoft.com/~joshuago/
Do they address the captcha-solving porn surfers attack?
http://catless.ncl.ac.uk/Risks/23.17.html#subj4
Ah, this one again :-)
I'd be very interested in any reference showing that that this "attack" has
actually been exploited.
cf. (may wrap)
http://www1.ietf.org/mail-archive/working-groups/asrg/current/msg09194.html
_______________________________________________
Asrg mailing list
Asrg(_at_)ietf(_dot_)org
https://www1.ietf.org/mailman/listinfo/asrg