July 30, 2010
Graphical Distorted Text
This is a traditional graphical CAPTCHA that requires the site visitor to read and then provide the character values within the distorted image. Below is an example of one of our images:



Give it a try. You you know you want to. :)

If you are looking to adopt this system for your site, here's the skinny on how to get it integrated:
  1. You need an existing web form that exposes functionality you want protected -- say a login form.
  2. You need to generate a random value that is 32 alphanumerical characters long.
  3. Embed this value in your existing form as a hidden element.
  4. Add an IMG tag near your form that is sourced to http(s)://areyouahuman.org/captcha.pl?id=[random value from #2].
  5. Users will need a place to enter the code found in this image, so you should add a text input to your form as well.
  6. After the form is submitted you need to parse out the hidden random value and the code entered by the user.
  7. Make a request to http:(s)//areyouahuman.org/captcha.pl?id=[random value from #2]&code=[value entered by user]&type=IMAGE.
  8. The response to this request will be either 'success' or 'incorrect'. Deny or grant the user's action accordingly.
If you want to control the dimensions of the image, simply add 'x' and 'y' parameters to the IMG request, like this:

http(s)://areyouahuman.org/captcha.pl?id=[random value from #2]&x=250&y=80

This results in the following image:




Want Code?
We have full blown working demos along with source code (PHP, PERL, C#) for integrating this stuff into your site! Grab 'em over in our Community page. If you have any other question feel free to contact us.