I had some discussions with the w3c protocols and formats working group
(the folks working on ARIA among other things) about captchas last year
and am pasting what I said here:
In the end the browser is going to make an http connection to the server
to send a set of results and the server will analyze them to be true or
false. If somebody can generate that set of results algorithmically they
can hack the validation. Current methods rely on presenting a challenge
that requires human analysis which would be difficult for a computer
emulate. Presently these challenges consist of visual/audible captchas
and various linguistic/logic challenges. By definition then these
challenges require recognition of visual and aural objects and/or
solving contextual conundrums. This also means that any technique which
lowers the cognitive requirement is going to weaken the protection.
IMHO, protections reliant solely upon generating puzzles that only a
human can solve is going to yield diminishing returns over time. Either
the cognitive bar will rise to the point that only those with perfect
perception can get in or it will become low enough that the algorithms
will get through. Absent another reliable human identifier it boils down
to just another arms race.
CB
Greg Kearney wrote:
Well of course I think everything should be accessible. My solutions
while developed on a Mac should work in any environment as they are
PHP based.
Greg Kearney
535 S. Jackson St.
Casper, Wyoming 82601
307-224-4022
[EMAIL PROTECTED]
On Apr 16, 2008, at 5:27 PM, Scott Berry wrote:
Greg,
I'd like to see how you feel about this. I use a sweepstakes site
that when
you report broken links and things of that nature their number is
legible
for the blind at the bottom by their edit box to put the number in.
Currently, I use Windows as it is my preferred platform but I think
captia
like this should be implemented more. How do you feel about such sites
making the numbers readable?
Have a wonderful day.
You may contact me at:
Scott Berry
Hotmail: [EMAIL PROTECTED]
Northlc.com: [EMAIL PROTECTED]
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Greg Kearney
Sent: Wednesday, April 16, 2008 4:27 PM
To: General discussions on all topics relating to the use of Mac OS X by
theblind; macvoiceover; Iain Murray; Acb List
Subject: Accessible web design and CAPTCHA
For my continuing series on web design for accessibility I discuss
CAPTCHA the design and usability issues they represent as well as
offering an accessible alternative. For the page go to:
http://www.cucat.org/projects/navigation/captcha/index.php
To read my other papers on similar topics go to:
http://www.cucat.org/projects/design.php
Thanks for looking.
Greg Kearney
535 S. Jackson St.
Casper, Wyoming 82601
307-224-4022
[EMAIL PROTECTED]
