So, a while back, I threw together a quick commenting tool for use on guyblade.com
. At some point, it became spammy and I just disabled it. Based on the dates of posts, this was like two years ago. I was reminded that this page existed by looking at my awstats and seeing that, dispite the fact that it was impossible to actually post to the comment page, it was being spammed to the tune of a few hundred hits a month.
My response was, of course, to try to re-enable it with some sort of security. My first attempt was a brain-dead captcha made using PHP's gd library. Apparently, spammers have prebuilt libraries for solving any captcha using the built-in fonts in PHP's gd build as I had several hundred spam posts by the time I checked again.
My second attempt (the current one) is to present an equality of the form "x * y + z = t" wherein one of x, y, z or t is missing and all are non-negative integers. The user is prompted to solve for the missing value. Although it is also brain-dead simple, I hope that it is not in the pre-built captcha solving libraries. If it is, I may be forced to make people solve simple definite integrals over polynomials and/or evaluate simple derivatives at points on polynomials.
I suppose this could have the side effect of preventing some people from being able to comment on my posts @ guyblade.com, but I think it will be ok.
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