Introducing DISTCHA* An accessible CAPTCHA** slider (v0.2)

July 4th, 2010. By Samuel Sirois and Denis Boudreau.

This is yet, another attempt at killing CAPTCHA, based on HTML, CSS and a little touch of JQuery magic.

What we're trying to pull here is an alternative to the current CAPTCHA solution, which is inherently inaccesible to people with disabilities, despite the best efforts put forth by initiatives such as the popular reCAPTCHA or the more recent nuCAPTCHA.

An article by @lukew titled "A Sliding Alternative to CAPTCHA?" published on July 1st, 2010 introduced the idea of the slider approach to replace CAPTCHA, which we thought was brilliant. We decided to push this idea further and try to come up with a solution that would be device-independent, cross-browser and more importantly, totally compatible with assistive technologies. The goal here being to make sure it would be accessible to people with disabilities using assistive software or to people using touch screen devices such as the iPhone or the iPad.

The solution is not yet complete and still requires a lot of work. If you feel, like we do, that CAPTCHAs are broken and need to go away for good, feel free to experiment with various user agents, play around with the code or share your thoughts on this idea by submitting comments using the form below.

Updates

July 5th, 2010. Thanks to @jkiss for pointing out that the attribute aria-live could be use on the success message zone in order for screen readers to announce the change in the page provoked by successfully accomplishing the challenge.

Some people pointed out that the slider was not working with touch screens (@kliehm, @rikkiprince). However, some seem to be able to slide the cursor with a bypass gesture (@ppatel) on the iPhone: With Voiceover on, doubletap slider, hold on last tap for double tones, slide finger without lifting. @ppatel’s Twitter update. Further work is needed in this area and we're investigating.

Quite a few developers out there pointed out with reason that this DISTCHA mechanism wasn't secure to robots and that it could be quite easy to bypass the challenge (thanks to François Monette and @notabene). We haven't come with a correct challenge and have concentrated our efforts on the accessibility of the tool but we surely need to get to this if we wish DISTCHA to be an acceptable and practical alternative to CAPTCHA. After a discussion with @m_dupont, we've come with an hypotheses that is worth exploring. We are currently testing a way to have a random success position that could solve the challenge for humans and that wouldn't simply specify a secret value inside a hidden field. Of course, we'll keep you posted.

Thank you all for your comments and enthousiasm.

DISTCHA Proof of Concept

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