Slider CAPTCHA, a Different but Elegant Spam Killer for Wordpress
People having a blog or a website with a comment and/or contact functionality available know that the amount of spam received can be a true headache. In order to fix this issue there are many alternatives available, like external services like Askimet or the classic CAPTCHA. Confronted with this reality, the Multimedia and E-learning Division from the Instituto Superior Técnico (Technical Superior Institute), in Portugal, has developed a new validation system, alternative to the traditional CAPTCHAs we are used to see: Slider CAPTCHA.
Traditionally, the CAPTCHA (Completely Automated Public Turing test to tell Computers and Humans Apart) is a cognitive challenge consisting in the copy of a distorted word or numbers where, supposedly, every time there is a positive validation, it was made by a human. We all know that this kind of tests is usually slow and annoying for users, forcing a break in the interaction with the whole system.
There are several problems with these tests: sometimes the words are illegible, sometimes the tests take lots of time to complete as people get mistaken and, more recently, there are ways for bots to overcome them, which defeats the initial purpose. Slider CAPTCHA, however, proposes an approach that is alternative, much more practical and without propensity for errors by the users. It also has a very well organized interface, visually stimulant, quick and compatible with mobile devices.
By using the administration panel inside Wordpress, administrators can also change the whole appearance of the Slider. It can be applied not only to the comments section, but also to other pages and functionalities, like registry forms or newsletter subscriptions. While the users does not slide the Slider, the data in the forms cannot be sent.
Regarding safety, this plugin has several algorithmic and mathematical validations in order to verify if there were any illegitimate and/or automatized tries to fool the validation mechanism. This Wordpress plugin is still under active development, so the developers are obviously taking suggestions to improve it.