Really Simple CAPTCHA

Really Simple CAPTCHA does not use PHP 'Sessions' for storing states, unlike many other PHP CAPTCHA solutions, but stores them as temporary files. This allows you to embed it into WordPress without worrying about conflicts. When you generate a CAPTCHA, Really Simple CAPTCHA creates two files for it; one is an image file of CAPTCHA, and the other is a text file which stores the correct answer to the CAPTCHA. The two files have the same (random) prefix in their file names. In this case, for example, when the respondent answers 'K5GF' as an answer to the 'a7hk3ux8p.png' image, then Really Simple CAPTCHA calculates hash of 'K5GF' and tests it against the hash stored in the 'a7hk3ux8p.txt' file. If the two match, the answer is confirmed as correct.

First, create an instance of ReallySimpleCaptcha class: $captcha_instance = new ReallySimpleCaptcha(); You can change the instance variables as you wish. Generate a random word for CAPTCHA: $word = $captcha_instance->generate_random_word(); Generate an image file and a corresponding text file in the temporary directory: $prefix = mt_rand(); $captcha_instance->generate_image( $prefix, $word ); Then, show the image and get an answer from respondent. Check the correctness of the answer: $correct = $captcha_instance->check( $prefix, $the_answer_from_respondent ); If the $correct is true, go ahead. Otherwise, block the respondent — as it would appear not to be human. And last, remove the temporary image and text files, as they are no longer in use: $captcha_instance->remove( $prefix );

Really Simple CAPTCHA is not strongly secure. If you need perfect security, you should try other solutions.

Really Simple CAPTCHA is intended to work with other plugins. It is originally created for Contact Form 7, however, you can use it with your own plugin.

If you wish to see a live sample of Really Simple CAPTCHA, you can try Contact Form 7.