Jeff at Coding Horror wrote a very good article on CAPTCHA's effectiveness.
CAPTCHA is an acronym for Completely Automated Public Turing test to tell Computers and Humans Apart invented at Carnegie Mellon University and named as an homage to Alan Turing.
According to Jeff Atwood's tests in the article mentioned above, just a simple, even static CAPTCHA stopped over 99% of the comment SPAM. A pain to be sure, but a way of life nowadays.
I do not get many comments, if any, but CAPTCHAS are on for his same reasons. I do have to battle the scourge of SPAM in a couple of Wikis I work with daily, where CAPTCHA's are not a good solution (for an open Wiki). It is not fun to keep these idiots at bay.
Tuesday, October 31, 2006
Excellent article on CAPTCHA's effectiveness
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Hey Alex,
ReplyDeleteI had a bunch of wiki spam happening but wasn't able to easily implement CAPTCHA since my wiki is still using traditional ASP (not ASP.NET) - however, I implemented something that has been so far %100 effective at stopping spam bots. In order to edit a topic you must set a cookie by entering your name in a field and clicking save. The cookie lasts for a couple weeks so you don't need to do it on every edit. So this may be a solution for your wiki without reverting to CAPTCHA.
Try it out to see what I mean. Double click a wiki topic to try and edit.
http://randyjean.no-ip.com/openwiki