CAPTCHA Alternatives Abound

After my earlier post about an alternative approach to CAPTCH that I discovered today, I decided to spend a few minutes looking at what alternative approaches are being used and how accessible they are to programmers. I must say I was impressed by my findings, particularly since I focused this particular search only on WordPress plugins.

Why WordPress? Three reasons:

  1. I've been studying WordPress lately for some actual site work I'm doing for myself and two clients.
  2. WordPress has such a huge following that it borders on being a standard.
  3. It is pretty easy to find WordPress plugins without spending hours rummaging around the Web's attic.
I found that several different CAPTCHA approaches are available as easy-to-configure plugins for WordPress, including:

  • Saber which allows you to choose from among image, math or text tests, set the complexity of math challenges, email link confirmations before post, and a number of other altrnatives
  • NoSpamX uses an interesting idea of creating hidden form fields that a human wouldn't see and therefore wouldn't fill in but that a spambot would find and fill in because it blindly fills in all fields on a form.
  • WP Captcha-Free creates two hashes, one for login and one for comment post and compares them to detect the probability that a bot is at work.
  • WP-NOTCAPTCHA takes an interesting approach. It presents the user with three icons and instructs him or her to rotate them so they are properly oriented. I find this one particularly intriguing because not only would it seem, at least, to be all but unbreakable, but it is language-independent as well.
  • Mollom is like NoSpamX and WP Catcha-Free in that it is transparent to the user. It uses intelligent text analysis to filter out probable spam and then confronts suspected spambots with a dynamic CAPTCHA challenge so that only suspects get the experience.
I'm sure there are libraries in PHP and other popular programming and scripting languages to implement these same strategies but clearly the world of CAPTCHA is one with lots of attention focused on it.

Posted via email from danshafer’s posterous

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February 6, 2010 · Posted in Web technology  
　　　　

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