Comments on: Captcha Breaking Experiment in PHP

By: Niloy

Niloy — Sat, 07 Feb 2009 21:00:41 +0000

That’s an excellent font you used there. For a while, I thought you had a graphics tablet and an excellent handwriting.

By: VistaArc

VistaArc — Sat, 24 Jan 2009 09:24:22 +0000

@Sabuj Kundu aka manchumahara – Certainly

@hasin Thanks, I went through this link before.

By: hasin

hasin — Sat, 24 Jan 2009 07:20:58 +0000

very interesting indeed. good work

have a look at http://www.cs.sfu.ca/~mori/research/gimpy/ – here is another interesting project to break captcha. see the variations they have done, just amazing.

By: Sabuj Kundu aka manchumahara

Sabuj Kundu aka manchumahara — Sat, 24 Jan 2009 06:30:51 +0000

I read about the Nadim’s blog and now this one. Got fan of u both . I think I will try to do some experiment soon.

By: Kurt Alfred Kluever

Kurt Alfred Kluever — Sat, 10 Jan 2009 19:26:35 +0000

@Nadim: You mentioned the Video CAPTCHA…that was my thesis topic . Here’s more info about it and a link to a demo: http://www.kloover.com/video-captchas/

@VistaArc: I tested a few different classification methods for breaking the PayPal CAPTCHA (including vertical and horizontal projections as you have done). The writeup and full MATLAB source code are up on my site: http://www.kloover.com/projects/paypalhip/

By: Nadim Jahangir

Nadim Jahangir — Sat, 10 Jan 2009 17:42:13 +0000

thanx,
u seem an interesting guy. keep in touch. would love to have chat with u later on

By: VistaArc

VistaArc — Sat, 10 Jan 2009 13:25:07 +0000

@Nadim Jahangir

Thanks bro, Ya I know . First of all, Edit Distance is not a appropriate approach you know I wanted to use Neural Networking. But then think I should use something simple to break this simple captcha [Mosha marte kaman keno???] , Even it can be broken with distribution formulas [sounds funny though] . Here for this simple captcha Edit Distance has some tolerance, but it is ignorable. No one mind if 1 is fault among 10000 . So, for complex captchas it will be like 9000 faults in 10000. lolz

Hmm, After their bad experience with Audio Captcha they are now dealing with Video. Actually, Audio captcha is easier to break than Visual capthca. And, Ya its really fun doing this.

BTW, Keep doing your great jobs. Your projects are really awesome.

By: Nadim Jahangir

Nadim Jahangir — Sat, 10 Jan 2009 13:07:47 +0000

nice job bro.
u used Edit Distance and it works for such simple captcha. but did u try with complex ones ? lower fault tolerance of edit distance fails to cope with complex ones nice attempt though keep doing naughty jobs it’s fun, isn’t it ? for such naughty guyz like u n I, some more advanced captcha schemes have already been developed like Video Captcha, have u heard of it ?

By: Mehdi Hasan

Mehdi Hasan — Fri, 09 Jan 2009 13:14:08 +0000

Good job mate!

By: Russell

Russell — Thu, 08 Jan 2009 02:59:59 +0000

LOL good good!