Comments on: Math Captcha Component

By: Jamie

Jamie — Fri, 11 Jun 2010 22:11:16 +0000

Hi Morgan,

I haven’t experienced that problem on Chrome, which is my main development browser. But thanks for the heads up – hopefully it’ll be useful information for other visitors.

By: Morgan Leininger

Morgan Leininger — Thu, 10 Jun 2010 20:48:13 +0000

Hi Jamie,

Thanks so much for sharing your code; this component seems a much better alternative than the terrible image based CAPTCHAS so prevalent today.

I have encountered a very strange bug with this component and Chrome (the browser). I am fairly sure the bug is with Chrome (I know, I know, it’s a purely server side component except insofar as Sessions involve a cookie…but it’s true). I have reported it to them.

I am using the stable CakePHP 1.2 branch. This component works as expected with IE 7, Firefox 3, and Safari 4. However, Chrome only a minute fraction of the time displays a question which is the correct answer to the value of the mathCaptcha written to Session. And that’s obviously just random probability based on the 1-5 min/max and + operand constraints.

My guess is that maybe Chrome does something different with .htaccess redirects that CakePHP is using in the course of processing requests. And/or it’s related to the way Chrome will grab “bad” URLs before Comcast…

In case you aren’t aware, Comcast has taken to sort of hijacking bad DNS requests; mistype a domain and you get a Comcast search page. Chrome (alone of the major browsers AFAIK) “pre-hijacks” those requests…which is a bit scary being as how they must essentially use their own DNS servers in preference to what I have set in my OS…

But in any case…it appears they somehow load the page twice very quickly. One run of $this->MathCaptcha->generateEquation() is sent to the display and a second run of $this->MathCaptcha->generateEquation() gets written to Session (though I’m not currently sure of the order).

Sadly, now that my brain is completely obsessed with this, I’ve been asked to ignore the Chrome users for now (they will almost never be able to validate a Simple Math Captcha, except for the few random equation collisions), but with Chrome creeping towards 15% in some estimates…

If you have any potential insights on this issue I’d love to hear them. If I hear back from the Chrome crew or crack this in some other way I’ll post back.

Thanks again for sharing.

By: Jamie

Jamie — Sun, 07 Feb 2010 20:07:03 +0000

Sorry Todd – I’ve just been really busy lately, I haven’t been able to pay much attention to my blog or any of my public code. You’re right, I mistakenly put the operand option there before finishing that feature. To be honest it’s not a priority for me at this time, so I’ll probably just take out the option before I add support for multiple operands.

By: Todd

Todd — Sun, 07 Feb 2010 19:12:21 +0000

Well I guess not. This works good for just adding numbers but thats it. I had to redo the whole thing to use subtraction.

By: Todd

Todd — Wed, 20 Jan 2010 02:14:08 +0000

I noticed you have the option to adjust the settings like the “operand” but if you change it to – then it returns negative numnbers. Any plans on fixing it to work correctly with subtraction?

By: Daniel

Daniel — Wed, 13 Jan 2010 05:18:42 +0000

I love this component. It’s easy to integrate and works like a charm. Good job!

By: Jamie

Jamie — Wed, 01 Jul 2009 14:12:54 +0000

Apparently it’s thanks my complete inability to use the WordPress scheduling tool properly. And that broken link was fixed within minutes – I can’t believe Google still picked it up! Yeesh. Thanks for the heads up.

By: Jamie Nay » Simple Math Question Captcha Component for CakePHP

Jamie Nay » Simple Math Question Captcha Component for CakePHP — Wed, 01 Jul 2009 14:08:56 +0000

[...] Math Captcha Component [...]

By: deizel.

deizel. — Wed, 01 Jul 2009 12:20:50 +0000

Hi Jamie, not sure if you accidentally published this too soon then hit unpublish, but just a quick heads-up to let you know that it has appeared in Google Search and Google Reader with a broken link. Also, you can find it with your site search although it isn’t published to the front page of your blog. Useful component though!