Re: Audio CAPTCHA review request

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 -- ------- http://sperling.com http://ancientstones.com http://earthstones.com