Complete Working Script and Implementation Technique - PHP

You can see a fully working example here, based on the code discussed previously:

http://www.php-developer.org/asirracaptchaform.php 

You can download the complete script here: http://www.php-developer.org/wp-content/uploads/scripts/asirracaptcha.txt  

Implementation Tips

1. When you download the script at the link above, you'll see detailed instructions for how to add the Asirra code blocks into your existing PHP web application.

2. There are around five code blocks to be added to your application. These blocks of code can be integrated as simply as performing copy and paste. No further configuration required, except for some minor tweaks on how the dog/cat images will be displayed on your form.

3. If you would like to use a much cleaner code and implement through several pages dynamically, you can further modify the script and maybe use PHP includes. In that case, however, you need to be more careful about security and the coding details.

Important note: According to Microsoft, “Asirra is still in beta testing; the service and its API may both be unstable.” And the following are some weaknesses of Asirra captcha system:

1. Currently, it contains no support for audio captcha features (useful for the blind).

2. The captcha system is still in the beta testing stage.