On The Tutorial Blog today they've shared a library that you can use on your CodeIgniter application to help give your forms a bit more security - a math problem "captcha".
The class that we are going to create within CI will simply add a math question that the user will have to enter correctly to continue. This is useful to stop bots from mass submitting information to your forms. The class we are going to write is only very short and simple, but it will give you an idea of how to create classes for your own projects.
Their class creates two random numbers to be used for the question, displays the question the user should answer (Ex. "What is 2 + 4?") and sets the answer in the flashdata, ready for the page submit. When the controller reloads, the answer the user gave and the one from the flash are compared as a part of the standard form validation rules.