Wednesday, 18 July 2007

Human verification codes

I saw my first really interesting human verification code yesterday; instead of the CAPTCHA-style "type in the letters in the image" system, I was allowed to continue only after clicking on all the animals in a grid of 9 photos that "don't have fur" - so I clicked the seagull and the lizard and was on my way.

I think this is great - it was a really engaging way of getting me to do something onerous, as opposed to squinting at some hard-to-read gobbledegook. A friend mentioned he saw another with a simple arithmetic problem written out; he had to write the answer to "three plus seventeen"...

3 Comments :

Anonymous said...

You'll like this then:

http://research.microsoft.com/asirra/

The problem with this image based approach to CAPTCHA is that you'll need to have a large collection of images to begin with. Another example here using a large borrowed collection of images but the test itself is too subjective to be consistently human solvable.

http://www.hotcaptcha.com/

Thursday, July 19, 2007 8:21:00 PM  
Marcel Kornblum said...

I do like it!

I think the original one I saw was more charming (irritated I waited before posting - I can't remember where I saw it), but MS using it shows its a bit more intuitive and user-friendly than the distorted text idea.

Hotcaptcha is pretty funny, but TBH I think I'd probably score as a bot 1/3 of the time...

Thursday, July 19, 2007 11:07:00 PM  
Cameron said...

i got the cat question wrong! i thought i was a geek but really i'm a bot :-)

i've seen some other captchas which use simple arithmetic as verification. I think this would be quite easy to program as you can just have a number assigned to a picture of that number and have them randomly selected in any combination. i saw this on jonathan schwartz's blog:

http://blogs.sun.com/jonathan/

he's actually using text for the numbers in the question which could be a bit of a hole if a bot is specifically tailored for this form. i don't think this technique is used much tho so the bots probably wouldn't be able to handle it. Added to that, since he's the CEO of Sun i would imagine they keep a good watch on his blog... :-)

Friday, July 20, 2007 2:10:00 PM  

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