Comments on: Captchas for My Blog Comments

By: Dennis

Dennis — Thu, 25 Jan 2007 21:21:56 +0000

You really should try SpamKarma 2.

http://unknowngenius.com/blog/wordpress/spam-karma/

It does an amazing job of filtering out spam. Amazing.

By: mike

mike — Thu, 25 Jan 2007 20:16:07 +0000

BTW - Congratulations to Jeff for being the first poster to successfully solve the complex math challenges in our new comment captcha’s!

By: mike

mike — Thu, 25 Jan 2007 20:15:26 +0000

Expecting captchas to be broken seems pretty reasonable. The good news is that there are many different implementations. So, first to be knocked down will be the more important captchas for spammers to defeat - e.g. those at Google, Hotmail, etc. Then, if there are common implementations, those will get knocked down. And we’ll build tougher captchas.

The captcha on this site is an arbitrary question. You can set it to anything. I could set it to “What is Mike’s last name?” Sure, it could be defeated if a spammer really wanted to take me down. But they’ll be looking to defeat more important captchas and ones that they can knock down generically across many sites.

By: Jeff S

Jeff S — Thu, 25 Jan 2007 15:03:54 +0000

Math captchas? Neat.

Here’s a puzzle for you: What will happen to our online systems if and when captchas are defeated? In particular, the “What is the text in this image”-style captchas seem like they’re ripe to be defeated. As it’s been explained to me, solving these is really two problems:
1.) Identify the segmentation points between glyphs, and
2.) Identify a glyph in a region of the graphic among the noise.

At a conference I attended 2 years ago (CEAS), a paper was presented that showed that computers are about 2 orders of magnitude better at #2 than humans are. So now we’re down to solving #1.

So here’s my prediction: In 5 years, image style captchas as they are used today will not be effective anti-bot tools.