At 9:24 AM -0400 4/6/07, Robert Cummings wrote:
What I'm saying is that's it's a
fairly poor choice from an accessibility perspective.
I thought that as well, but it seems that at least visually impaired
users using screen readers don't have any problems with it.
Not that I have any support for this claim, but perhaps relying on a
screen reader requires it's use -- I don't know.
My audio captcha relies on javascript, namely ajax. The problem I had
was how to deliver the sound once the user requested it from the main
page. I used <bgsound> and <embed> tags to accomplish that after
browser sniffing. However, those tags had to be in a new page to
play, which required a refresh.
Why do you need to refresh? I had a DHTML/Ajax chat client I built and I
just pumped flash tags into a div to play tones when new messages were
detected. I didn't bother browser sniffing though, just made the
assumption that flash existed.
I tried flash, see:
http://sperling.com/examples/assorted-captcha/
but that required that flash to be turned on and not all visually
impaired users have a need for flash. In fact, if you do use flash,
then you have to tell them or they don't know what you're trying to
do.
It was much simpler to do it the way I did with just html.
I think in general, unless you're hosting a hugely popular site, few wil
attempt to custom crack your site's captcha -- there's an expected value
investment to going to the trouble. Perhaps a good system would be to
treat captcha algorithms like passwords, and change the way it works
every few weeks
I've thought about creating a database that would provide questions
and answers for my captcha's. That way I could add questions everyday
creating thousands of different combinations of simple questions.
However, this would require the user to have his own dB and update
his dB from my site periodically -- thus, a bit more sophisticated
user. I would be willing to do this once I'm convinced that this
method would be more accessible than any other.
However, it would be a simple matter for spammy to download all the
keys from my site and use them thus defeating the whole idea, duh.
So, if I was to support this method, then each capatcha user would
have to come up with their own questions, which could be problematic.
Need to think more.
Cheers,
tedd
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