Takayuki Miyoshi

<p>Really Simple CAPTCHA does not work alone and is intended to work with other plugins. It is originally created for <a href="https://contactform7.com/" rel="nofollow ugc">Contact Form 7</a>, however, you can use it with your own plugin.</p>
<p>Note: This product is “really simple” as its name suggests, i.e., it is not strongly secure. If you need perfect security, you should try other solutions.</p>
<h4>How does it work?</h4>
<p>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.</p>
<p>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.</p>
<p>The two files have the same (random) prefix in their file names, for example, “a7hk3ux8p.png” and “a7hk3ux8p.txt.” 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.</p>
<h4>How to use with your plugin</h4>
<p>Note: Below are instructions for plugin developers.</p>
<p>First, create an instance of ReallySimpleCaptcha class:</p>
<pre><code>$captcha_instance = new ReallySimpleCaptcha();
</code></pre>
<p>You can change the instance variables as you wish.</p>
<pre><code>// Change the background color of CAPTCHA image to black
$captcha_instance->bg = array( 0, 0, 0 );
</code></pre>
<p>See really-simple-captcha.php if you are interested in other variables.</p>
<p>Generate a random word for CAPTCHA.</p>
<pre><code>$word = $captcha_instance->generate_random_word();
</code></pre>
<p>Generate an image file and a corresponding text file in the temporary directory.</p>
<pre><code>$prefix = wp_rand();
$captcha_instance->generate_image( $prefix, $word );
</code></pre>
<p>Then, show the image and get an answer from respondent.</p>
<p>Check the correctness of the answer.</p>
<pre><code>$correct = $captcha_instance->check( $prefix, $the_answer_from_respondent );
</code></pre>
<p>If the $correct is true, go ahead. Otherwise, block the respondent — as it would appear not to be human.</p>
<p>And last, remove the temporary image and text files, as they are no longer in use.</p>
<pre><code>$captcha_instance->remove( $prefix );
</code></pre>
<p>That’s all.</p>
<p>If you wish to see a live sample of this, you can try <a href="https://contactform7.com/captcha/" rel="nofollow ugc">Contact Form 7</a>.</p>


Really Simple CAPTCHA

Needed this for an installation with custom forms. I used the plugin developers instructions and was able to make a fully custom implementation based on server side validation within 30 minutes. No more spam bots misusing the forms. Thank you!

Great work - easy to implement

Really Simple CAPTCHA is a CAPTCHA module intended to be called from other plugins. It is originally created for my Contact Form 7 plugin.

dotsquares

<h3>Form Stop Spam Emails – A permanent solution to stop spam emails</h3>
<p>“DS CF7 Math Captcha” plugin gives functionality of prevent unwanted spam to your contact form 7. Contact Form 7 plugin is most widely used by many users so this plugin helps to prevent unwanted spam from website that has been created by Contact Form 7 plugin. This plugin is very much effective to stop form spam for Contact Form 7 plugin.</p>
<h4>The plugin has been tested with the latest version (6.1) of Contact Form 7</h4>
<h4>Features</h4>
<ul>
<li>Math Captcha</li>
<li>Refresh Math Captcha</li>
<li>Available Translations – English (US), French, Hindi, Spanish and German</li>
</ul>


DS CF7 Math Captcha

Works Great

"DS CF7 Math Captcha" is a math captcha with refresh captcha functionality to prevent unwanted spam for your contact form 7 plugin.

Really Simple CAPTCHA vs DS CF7 Math Captcha