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Edinburgh Web Development

Next gen CAPTCHA is a No Captcha

by Iain Wilson

17 December 2014
Google reCAPTCHA

Don't know about you, but I'm pretty tired of using CAPTCHA images on web page forms.  

Here's a new facility along the same lines, but a whole lot easier for the user.

What's a CAPTCHA?

If you're not familiar with the term, CAPTCHA is a challenge-response test used on webpages to make sure the user is human.

It works by displaying a distorted image of some characters that the user must interpret and repeat into a form field.

The aim is to stop automatic software filling in your web forms with rubbish or worst still, trying to sabotage them with spam email.

They do a pretty reasonable job in that respect, but they are kind of a pain to use!  

Getting the CAPTCHA wrong means the form isn't submitted, but it is pretty easy to misread a character from the generated string.  Most people just haven't got the patience to try the CAPTCHA more than twice if they get it wrong.

Introducing reCAPTCHA

With all this in mind, Google have developed reCAPTCHA, a slightly different approach.

reCAPTCHA isn't based on repeating distorted text.  It simply shows the prompt "I'm not a robot" with a check-box the user must tick.

The reCAPTCHA API then evaluates the response of the inputter using a range of factors including mouse movements and time taken (not surprisingly, Google aren't giving a whole lot of information away here).

If these are outside set boundaries, more questions are asked until the software can make a decision.

In our tests (as humans) we've never managed to get it to ask further questions.  Not sure if this is good or bad.

Installing reCAPTCHA

To use reCAPTCHA on your own forms doesn't take much if you've got some developer skills.  

You need to sign up for the API and get your secret keys. Then it simply needs the addition of a Javascript library and a hidden POST field in your form page then a little check in your back-end validation to see if the user has been deemed legitimate.

Try it out

We've been using it on the Blot contact page for a few weeks now. It's an absolute breeze for visitors to use and automated responses are certainly not getting through.  

Interested in adding it to your site?  The reCAPTCHA resource pages have all the instructions.  If you haven't got the skills, get in touch with us.

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Iain Wilson is Director at Blot Design.     Follow on

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