Captcha are those blurry and transformed images that recently became so
popular on many websites that accept user-contributed content. They are
an unevitable consequences of spammers becoming more sophisticated.
My forum for Sumatra PDF recently received an annoyingly high amount of spam, so I decided to put an end to it. Or at least die trying.
I extended the FruitShow forum software with a captcha scheme I’ve stolen from CVSTrac software. It’s very simple: instead of showing blurry images, it asks people to enter a result of a very simple arithmetic expression, like 1+3.
It seems to work for CVSTrac so maybe it’ll stop spam on my forum as well (so far it’s been a couple of days without a single spam).
I’m counting more on obscurity of the method. While it would be easy to manually modify the spam bot to defeat this particular captcha, I’m hoping that no-one will bother to put the effort just so that they can spam one website.
FruitShow, by the way, rocks. It took me an hour and just a few lines of PHP to add this. Too bad it doesn’t seem to be developed anymore (3 months of checkin silence).
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