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Re: Captcha identify

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On Wed, Aug 13, 2014 at 1:43 PM, Chris Angelico <rosuav@gmail.com> wrote:
> There are alternatives that are both easier for legit people and
> harder for spambots. Some rely on the fact that humans read things two
> dimensionally, and scripts look at the underlying structure; so, for
> instance, random field names and cunning CSS to match them up with
> their labels can result in a form that's completely messed up in the
> source, but looks perfect to a user. Or you can put extra fields down
> that you can't see if the form's laid out properly.

Chances are that if these tricks mess up a spambot, they will also
mess up a screen reader.

> Or you can combine
> those sorts of tricks with a very simple challenge-response, like
> "What is one plus one?" that requires some specific value to be in a
> specific field - and if that value occurs in the wrong field, you
> throw the form back to the user.

If I ask my phone "What is one plus one", a very nice sounding voice
will tell me that one plus one is two. It takes some cleverness to
come up with a question that is likely to stump a machine but not
deter a human, so the pool of such questions will necessarily be
limited. Meanwhile, all the spambot has to do is flag the question for
a human to answer and store the answer somewhere, and the question is
now useless.

> For some reason, everyone's jumped on the "show some mangled
> text/numbers and ask the user to enter them" bandwagon, in the same
> way that everyone has gone for passwords that require
> lower/upper/digit/symbol and (in the most annoying cases) are actually
> length-limited to something stupid like 12 characters. Yes, maximum,
> not minimum. Grumble.

I've seen some captcha systems that I couldn't solve after a dozen
attempts, and I have no serious vision problems. It's a problem with
no easy solution, and as computers get more powerful the intersection
of {problems machines can't solve} and {problems humans can reliably
solve} grows ever smaller.

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Captcha identify Wesley <nispray@gmail.com> - 2014-08-12 00:04 -0700
  Re: Captcha identify Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2014-08-12 08:59 -0400
    Re: Captcha identify Wesley <nispray@gmail.com> - 2014-08-12 07:57 -0700
      Re: Captcha identify Chris Angelico <rosuav@gmail.com> - 2014-08-13 01:06 +1000
        Re: Captcha identify Denis McMahon <denismfmcmahon@gmail.com> - 2014-08-12 15:38 +0000
          Re: Captcha identify Chris Angelico <rosuav@gmail.com> - 2014-08-13 01:54 +1000
            Re: Captcha identify Wesley <nispray@gmail.com> - 2014-08-12 18:36 -0700
              Re: Captcha identify Chris Angelico <rosuav@gmail.com> - 2014-08-13 11:46 +1000
              Re: Captcha identify Ben Finney <ben+python@benfinney.id.au> - 2014-08-13 11:54 +1000
              Re: Captcha identify Rob Gaddi <rgaddi@technologyhighland.invalid> - 2014-08-13 09:28 -0700
                Re: Captcha identify Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-08-14 03:52 +1000
                Re: Captcha identify Chris Angelico <rosuav@gmail.com> - 2014-08-14 04:21 +1000
              Re: Captcha identify "Eric S. Johansson" <esj@harvee.org> - 2014-08-13 07:39 -0400
                Re: Captcha identify alister <alister.nospam.ware@ntlworld.com> - 2014-08-14 11:42 +0000
                Re: Captcha identify Denis McMahon <denismfmcmahon@gmail.com> - 2014-08-14 23:19 +0000
                Re: Captcha identify "Eric S. Johansson" <esj@harvee.org> - 2014-08-15 13:18 -0400
                Re: Captcha identify Chris Angelico <rosuav@gmail.com> - 2014-08-16 03:30 +1000
              Re: Captcha identify Chris Angelico <rosuav@gmail.com> - 2014-08-14 05:27 +1000
              Re: Captcha identify Chris Kaynor <ckaynor@zindagigames.com> - 2014-08-13 12:24 -0700
              Re: Captcha identify Chris Angelico <rosuav@gmail.com> - 2014-08-14 05:43 +1000
              Re: Captcha identify Joel Goldstick <joel.goldstick@gmail.com> - 2014-08-13 15:44 -0400
              Re: Captcha identify Skip Montanaro <skip@pobox.com> - 2014-08-13 14:55 -0500
              Re: Captcha identify Tim Chase <python.list@tim.thechases.com> - 2014-08-13 15:01 -0500
              Re: Captcha identify Ian Kelly <ian.g.kelly@gmail.com> - 2014-08-13 14:16 -0600
                Re: Captcha identify Peter Pearson <ppearson@nowhere.invalid> - 2014-08-14 18:37 +0000
                Re: Captcha identify Ian Kelly <ian.g.kelly@gmail.com> - 2014-08-14 13:42 -0600
                Re: Captcha identify "Eric S. Johansson" <esj@harvee.org> - 2014-08-14 15:43 -0400
                Re: Captcha identify alex23 <wuwei23@gmail.com> - 2014-08-15 17:03 +1000
                Re: Captcha identify Mark Lawrence <breamoreboy@yahoo.co.uk> - 2014-08-15 09:14 +0100
                Re: Captcha identify Chris Angelico <rosuav@gmail.com> - 2014-08-15 08:22 +1000
              Re: Captcha identify "Eric S. Johansson" <esj@harvee.org> - 2014-08-13 16:42 -0400
              Re: Captcha identify Ian Kelly <ian.g.kelly@gmail.com> - 2014-08-13 14:18 -0600
              Re: Captcha identify Chris Angelico <rosuav@gmail.com> - 2014-08-14 09:13 +1000
              Re: Captcha identify Denis McMahon <denismfmcmahon@gmail.com> - 2014-08-14 23:15 +0000
                Re: Captcha identify Ben Finney <ben+python@benfinney.id.au> - 2014-08-15 13:23 +1000
              Re: Captcha identify Michael Torrie <torriem@gmail.com> - 2014-08-15 09:20 -0600
  Re: Captcha identify Denis McMahon <denismfmcmahon@gmail.com> - 2014-08-12 13:51 +0000

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