29 January 2009, 13:16

Hi, all. Long time surfer, first time commenter.

A few of my users are reporting that our Mahara installation always refuses to pass valid responses to CAPTCHA challenges in register.php. That is, while most users are able to successfully pass the CAPTCHA challenge when trying to register a new account, there are a few users who consistently fail to pass the challenge, particularly when they enter the correct strings. My website is www.c3ontario.com.

It's unrelated to browser type. I've had people using the same browser version on the same operating system version but on different machines have different results from the CAPTCHA challenge. I have confirmed that the server setup does not play any role whatsoever in this experience. Cookies are enabled. Unicode UTF-8 character sets are always used. 

I cannot reproduce this error myself. I upgraded to 1.0.9 but the behaviour remains. I'm at a complete and total utter loss. 

I was wondering if anybody could please describe briefly how the CAPTCHA challenge part of the software is organized. That way, I can try to trace through the code and figure out what may be going wrong. It's never easy to understand other developer's AJAX implementations.

Thank you very much for you attention. As well, thank you for developing such a spectacular system!

29 January 2009, 13:27

To add to my question, can anyone tell me if the CAPTCHA part of the system uses unusual TCP ports or anything like that

29 January 2009, 14:07

To add even more info, here's the output of gd_info (in case it helps):

array(12) { ["GD Version"]=> string(27) "bundled (2.0.34 compatible)" ["FreeType Support"]=> bool(true) ["FreeType Linkage"]=> string(13) "with freetype" ["T1Lib Support"]=> bool(false) ["GIF Read Support"]=> bool(true) ["GIF Create Support"]=> bool(true) ["JPG Support"]=> bool(true) ["PNG Support"]=> bool(true) ["WBMP Support"]=> bool(true) ["XPM Support"]=> bool(true) ["XBM Support"]=> bool(true) ["JIS-mapped Japanese Font Support"]=> bool(false) }

29 January 2009, 15:10

Hi Andrei!

The way the captcha works is this:

when it's displayed in the form, the value gets written to the user's session
when the form is submitted, the post value is compared with the session value.

I'm not sure why users would be having intermittent trouble.  You can disable captchas completely though - try setting $cfg->captcha_on_register_form = false; in your config.php :)

13 March 2009, 17:50

I never thanked you, Penny. Thanks!!!!

17 March 2009, 4:22

welcome! :)