Revision 2.2.1 (2021-11-23)
About: 'Crypto Captcha' (formerly 'CryptograPHP') limits spam in your gallery by adding a captcha in forms for registering, commenting and from the 'ContactForm' plugin.
It works like P@t's plugin 'Captcha' except that it uses the Securimage generator (www.phpcaptcha.org) instead of reCAPTCHA (www.google.com/recaptcha).
Compatible with 'Comments on Albums', 'GuestBook' and 'Contact Form' plugins.
Changes: Compatibility with Piwigo 12
Revision 1.0.9 (2018-11-25)
About: A small and lightweight Captcha solution to keep your installation free from bot spam comments and bot fake registrations.
It does not rely on any remote resources - like Recaptcha from Google or any others. This means you do not have to mention it in your GDPR compliance declaration. If Google enables Recaptcha V3 soon, Recaptcha will act like a tracker, since the advice is to implement it on every single page of your website. You will dislike Google for this, hopefully.
Installation is as easy as with any other plugin. Since this plugin does not use any database tables it does not matter which MySQL version you are using.
The Captcha works the classic way. There are some configuration options like colors, OCR confusion, dimensions and length of challenge. Just explore the possibilities in the plugin area of Piwigo admin.
Yes, it is the 5th or so Captcha solution, but all other solutions rely on remote resources or are not maintained anymore.
You can protect comments below pictures, comments below categories (plugin Comments on Albums), user registration, guestbook entries (plugin GuestBook) and the contact form (plugin Contact Form).
The plugin is based on work of mistic and Stefan Petre.
Would love to receive feedback.
Changes: Added support for Guestbook and Contactform, Bugfix in session house keeping, added some credits for those this work is based on (mistic, Stefan Petre)
Revision 2.8.a (2016-03-16)
About: Fight against spammers with additional checks (stopforumspam.com)
Changes: New languages:
* Czech (Česky [CZ])
* English [GB], thanks to Pat2309
Revision 2.7.a (2014-09-09)
About: Checks user comments for spam using the online service
Changes: -compatibility with piwigo 2.7
Revision 1.2.0 (2014-08-30)
About: A fun antibot system for comments, registration, ContactForm and GuestBook.
It's not a captcha, it provide two different challenges (for now) : a tic-tac-toe minigame and a drag & drop verification.
Can be used with Crypto Captcha ONLY if not activated on the same pages.
Changes: Compatible with Piwigo 2.7