QR code (or others) as a captcha?

Site Admin Joined: Jun 04, 2004 Posts: 6433

Any thoughts on using a QR code like the one below as a captcha for mobile phone apps that are QR code enabled?

registered · Posted: Thu Mar 11, 2010 6:10 am

Captcha fails, why not implement smarter post detection and get rid of captcha?

I can prove smart ways reduce spam for 99.9% and that is without captcha!

Posted: Thu Mar 11, 2010 8:58 am

Agreed. I was discussing this with someone who wrote a PHP QR code generator, and he pointed out that the QR code could easily be detected by bots.

Please tell us more about your smart ways to reduce spam...

Posted: Thu Mar 11, 2010 1:14 pm

Here's a simple one:

Code:

$ua_id = md5($_SERVER['HTTP_USER_AGENT']);


if ($_SESSION['UA_ID'] !== $ua_id) {


    exit('POST not allowed');


}

And a harder one:

Code:

if (preg_match_all('#<[^>]+>#s', $msg)


 || 1 < preg_match_all('#http://#i', $msg)


 || preg_match_all('#viagra|cialis|pfizer#i', $msg))


{


    exit('not allowed');


}

Posted: Thu Mar 11, 2010 2:42 pm

a news headline captcha:

Grab a (free)feed from another website , take it's news headline.
Let the visitor read it and type the headline into the validation field.

It will result in a big big visitation of bots to these website's , and the net to the used ip adresses becomes smaller and smaller.it takes time but i think that is the most effective way to exclude unwanted bots.unifying is the key.

ofcourse there can be other variations in association with another website.
The news headline is just on of it.

Posted: Thu Mar 11, 2010 4:51 pm

Oh, I thought you might be referring to something like Akismet (which Guardian has done some work on and is included in our Lust Factors.