So, I learned a few new things today.
You know those challenge dialogs which ask you to look at a distored picture of numbers/letters, decipher them, and type them into a box, something that a human can do fairly easily, but is extremely difficult for a computer to do; typically as a method to prevent automated computer entries into a web page?
Well, those things are called a CAPTCHA, which is based on something called a Turing Test.
Well, doing a Google using CAPTCHA as the search phrase yields lots of hits. While the top rated ones seem to be related to CAPTCHAs written for .asp or .net, if you hunt, you can find ones for perl or php. Here is a link to a php script.
Doing a search using: captcha movable yields lots of hits including a nice implementation specifically for Movable Type written by James Seng called MT-Scode. Its installation is a bit more involved, and requires the installation of a couple of additional modules on the web server.
MT-Scode Quick Links:
- Download latest mt-scode
- You need GD for this plugin to work
- You also need GD.pm
I also found the very interesting Six Apart Guide to Comment Spam which frowns on CAPTCHAs because of their negative effect on accessibility, but offers lots of good suggestions to managing/mitigating comment/trackback spam.
The big question is my mind is...
Do I implement a CAPTCHA, which would take quite a bit of time up front but which should allow me to re-enable the subscriptions and significantly reduce the time I spend removing spam, or do I just spend the few minutes a day with MT-Blacklist to delete the spam and rebuild the blog?
Considering that I've yet to have someone complain about the removal of the subscriptions - or the fact that they didn't work for so long, at least for the moment, I think I'll stick with the latter, but at least I've now documented an alternative, should I get inspired...
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Posted by David at December 04, 2006 04:50 PM