Cryptographp_XH is a CAPTCHA plugin based on cryptographp by Sylvain Brison. It was modified to fit in the CMSimple environment, can be called multiple times on the same page, and offers an alternative audio CAPTCHA. It can be used as utility plugin by other plugins, such as Advancedform_XH, to deter spambots from successfully submitting forms.
It requires CMSimple_XH ≥ 1.6.3 and PHP ≥ 5.4.0 with the gd and session extensions. It is released under GPLv3.
Cryptographp_XH couldn't be tested so far in various environments. It is a so called beta version. Use with caution!
A demo is available online; (try to) write a comment. Changes are listed in the changelog. For further details you can read the manual online.