I already discussed what I think about [[CAPTCHA

PHPBB2 and Anti-spam]] and how I can’t see it work, ever. Instead I suggested [[Textual Confirmation

http://bbantispam.com/tc/]] which sounds more sane to me.

A [[recent story

http://news.bbc.co.uk/1/hi/technology/7067962.stm]] shows that things are worse for CAPTCHA than I thought: not only can you program computers to recognise the letters, but you can also just carry the CAPTCHA to other sites for humans to solve for you. We’ve known about the possibility for a while now, and it’s been done for sure.

This has implications about Textual Confirmation, too: our questions could also be taken and asked to someone else. However, we can defend against that: we simply need to only ask questions that are related to our site, instead of generic questions. That way, ‘porting’ the question to a different site doesn’t work anymore, as the context surrounding the question has changed.

For example, ‘what is the capital city of France’ is a bad question: anyone can answer that (with or without the help of Wikipedia :-) ). On the other hand, ‘what is the name of the forum’s founder’, ‘in which city do we meet?’ are questions that only make sense in the context of a specific Web site.