How would I go about defeating a Captcha? I specifically need help with turning the text in the image into a character array or string. Is there a particular set of algorithms that I should be looking at?
+2
A:
Three options
1, Develop state of the art OCR faster than the captcha writers can generate more difficult captchas.
2, Use man in the middle attacks, reuse the captcha in your own site where you have some content somebody is prepared to enter a captcha to access
3, pay somebody in $THIRD_WORLD_COUNTRY a few cents/hour to break them for you
Martin Beckett
2010-09-07 04:31:32
#2 is freaking genius. I never even thought about doing something like that.
2010-09-09 04:11:50
@user441072 - it's apparently very common. Normal technique is to use access (or promised access) to some adult material. The combined computing ability of all the horny males on the internet is rather large.
Martin Beckett
2010-09-09 16:39:47
A:
Hmm... I could develop OCR software.
- Create set of "skeletons" of every letter and character on the keyboard.
- Pass Captcha through image filters to acquire desired characters.
- One at a time: draw line through the inside of the desired character, and compare it to the skeletons. If it matches a skeleton to a certain degree, assume that it is the character that the skeleton represents.
and voila! OCR software that can also break any captcha (possibly except ones that warp the shape of the letters too much).
I know it's probably not half as simple as I'm making it sound, but it's still possible.