= PWNtcha - captcha decoder =

PWNtcha stands for "''Pretend We’re Not a Turing Computer but a Human Antagonist''", as well as ''PWN capTCHAs''. This project’s goal is to demonstrate the inefficiency of many captcha implementations.

For an overview on why visual captchas are a bad idea, see Matt May’s excellent presentation, [http://www.w3.org/2004/Talks/0319-csun-m3m/slide1-0.html Escape from CAPTCHA], as well as the W3C’s [http://www.w3.org/TR/turingtest/ Inaccessibility of Visually-Oriented Anti-Robot Tests] working draft.

== History ==

I created PWNtcha in 2004 as a personal research project, but only published my results, not the program itself. Given the number of captcha-breaking software available for sale now, I changed my mind and decided to publish the PWNtcha source code. It can be downloaded from Subversion:
{{{
 svn co svn://svn.zoy.org/libcaca/pwntcha/trunk pwntcha
}}}
Note that PWNtcha is now lagging 3 years behind captcha technology and is therefore no longer a very interesting piece of software.

== Defeated captchas ==

PWNtcha is able to detect and decode the following captchas: 

|| Origin || Samples || PWNtcha efficiency || Comments ||
|| Authimage || [[Image(source:/pwntcha/testsuite/authimage/authimage_046.jpeg)]] [[Image(source:/pwntcha/testsuite/authimage/authimage_090.jpeg)]] || 100% || Vendor site: http://www.gudlyf.com/index.php?p=376 [[BR]] Weaknesses: constant font, aligned glyphs, constant glyph position, constant rotation, no deformation, non-textured background, constant colours, no perturbation. ||
|| Clubic || [[Image(source:/pwntcha/testsuite/clubic/clubic_000.png)]] [[Image(source:/pwntcha/testsuite/clubic/clubic_001.png)]] || 100% || Weaknesses: constant font, no rotation, no deformation, aligned glyph, constant background, weak colour variation, weak perturbation. ||
|| linuxfr.org || [[Image(source:/pwntcha/testsuite/linuxfr/linuxfr_014.png)]] [[Image(source:/pwntcha/testsuite/linuxfr/linuxfr_022.png)]] [[Image(source:/pwntcha/testsuite/linuxfr/linuxfr_081.png)]] || 100% || Weaknesses: constant font, aligned glyphs, no rotation, no deformation, non-textured background, weak colour variation, weak perturbation. ||
|| LiveJournal || [[Image(source:/pwntcha/testsuite/livejournal/livejournal_003.png)]] [[Image(source:/pwntcha/testsuite/livejournal/livejournal_015.png)]] || 99% || Weaknesses: constant font, constant character position. ||
|| lmt.lv || [[Image(source:/pwntcha/testsuite/lmt/lmt_000.png)]] [[Image(source:/pwntcha/testsuite/lmt/lmt_001.png)]] [[Image(source:/pwntcha/testsuite/lmt/lmt_002.png)]] || 98% || Weaknesses: constant font, almost aligned glyphs, no rotation, no deformation, constant background, no colour variation, weak perturbation. ||
|| Ourcolony || [[Image(source:/pwntcha/testsuite/ourcolony/ourcolony_001.gif)]] [[Image(source:/pwntcha/testsuite/ourcolony/ourcolony_002.gif)]] || 100% || Weaknesses: constant font, no rotation, no deformation, no colour variation, no perturbation. ||
|| Paypal || [[Image(source:/pwntcha/testsuite/paypal/paypal_000.jpeg)]] [[Image(source:/pwntcha/testsuite/paypal/paypal_001.jpeg)]] || 88% || Weaknesses: constant font, almost aligned glyphs, no rotation, no deformation, constant background, no colour variation, no additional perturbation. ||
|| phpBB || [[Image(source:/pwntcha/testsuite/phpbb/phpbb_015.png)]] || 97% || Vendor site: http://www.phpbb.com/ [[BR]] Weaknesses: constant font, no rotation, no deformation, constant colours, weak perturbation. ||
|| Scode and derivatives || [[Image(source:/pwntcha/testsuite/scode/scode_000.png)]] [[Image(source:/pwntcha/testsuite/auditor/auditor_022.png)]] [[Image(source:/pwntcha/testsuite/scode/scode_001.png)]] || 100% || Vendor site: http://james.seng.cc/archives/000145.html [[BR]] Weaknesses: at most 3 different fonts, no rotation, no deformation, weak colour variation, useless perturbation (separate colour key). ||
|| Slashdot || [[Image(source:/pwntcha/testsuite/slashdot/slashdot_009.jpeg)]] [[Image(source:/pwntcha/testsuite/slashdot/slashdot_010.jpeg)]] || 89% || Weaknesses: constant font, no deformation, constant colours, weak perturbation. ||
|| vBulletin || [[Image(source:/pwntcha/testsuite/vbulletin/vbulletin_000.jpeg)]] [[Image(source:/pwntcha/testsuite/vbulletin/vbulletin_001.jpeg)]] || 100% || Vendor site: http://www.vbulletin.com/ [[BR]] Weaknesses: constant font, fixed glyph position, no rotation, no deformation, almost constant colours, weak perturbation. ||
|| Xanga || [[Image(source:/pwntcha/testsuite/xanga2/xanga2_000.jpeg)]] [[Image(source:/pwntcha/testsuite/xanga2/xanga2_024.jpeg)]] || 49% || Weaknesses: fixed horizontal glyph position, no rotation, no deformation, constant colours, insufficient perturbation. ||