DEPRICATED: This plugin is no longer supported. Instead you should use something like DR Dave’s Spam Karma 2, as this not only processes your visitors posts, but also provides a captcha defence if the post is mildly supsect (It excludes efinately suspect posts completely).

The notes below are for people who have the plugin already.

This plugin allows you to add a little more anti-electronic commenting securtiy to your site. It provides a graphic that displays a word that must be entered so the post can be added.

There is a lot of random selection of background colours and text colours as well as levels of noise on the background. More noise, the less chance a computer has of cracking it… similarly the less chance a human poster has as well.

The default options allow for a light background and lettering with the drop shadow for the main word being in a contrasting foreground colour. Adding some extreme noise causes an almost unintelligable display. The two extremes are outlined below.

Demo captcha Demo captcha

One other question that you could ask about noise is “Isn’t a graphic in itself enough?" and for the most part - yes. It is rare that any spammer will be filtering blogs and trying to digitally process images. This means that you could switch off all the noise and set the rotation to zero.

Because of the contrast cut-off, even if the image was digitally processed, the actual letters get filtered out with the background - it’s only the drop shadow that is in the foreground colour, but this is enough for a human to pick out the lettering.

Once I work out how to add this to the account sign-up screen then you may want to add some more complexity.

For more information on CAPTCHA, you can check this out.

Plug-in installation and activation

Theme update

Firstly, you need to modify your theme to have an element the plugin can identify in the comments posting section.

You should open your comments.php file that can be found in your active themes directory (found on the presentation panel in the admin section). You should then search for the posting form and the author element. You should search for id=“author” or try single quotes if that does not work.

Above this line, you should add the following.

<div id="comment_captcha"></div>

Install and enable

Unzip the plug-in into your wp-content/plugins directory. In your plug-ins admin panel you should enable the plug-in. Once enabled, there should an Captcha heading on your options menu.

Add fonts

You should also add some fonts into the plugins directory. Fonts are selected at random and the more whacky the font, the more difficult it is to decypher - for humans as well mind you.

Parameter explanation

Maximum rotation angle

Each character in the word is rotated a random number of degrees. This parameter indicates the furthest rotation that should be used. The default is 30.

Mixed case display

While the check itself is case insensitive, you can display the characters as mixed case to add more complexity to your image. The default is unticked.

Random noise

The type of noise is selectable and can be applied all the time, or you can allow for randomness in the choice from all the available options. The default is unticked.

Noise » Letters

random letters can be applied in the background. This generally provides a good balance between computer confusion and human readability. The default setting is ticked.

Noise » Horizontal and vertical lines

A grid can be added behind the letters for extra confusion. The default setting is unticked.

Noise » Arches

Random sections of an elipse can be added in the background. The default setting is unticked.

Noise » Horizontal and vertical wiggles

A horizontal or vertical ‘wiggle’ can be added infront of the letters for extra confusion. The default setting is unticked.

Colour settings » Horizontal and vertical wiggles

The vertical ‘wiggles’ can be drawn in either the foreground or background colour set. Selecting this box will force the wiggle into the foreground colour set. The default setting is unticked.

Colour settings » Random background

The colour set is split into lights and darks for contasting - one being applied to the background (and letters themselves) and one to the foreground (letter shadow). Enabling random selection means the forground and background can be either option. The default setting is unticked.

Colour settings » Light background

If you are not using a random color selection, should the bacground colour set be the light option. The default setting is ticked.

Release history

Version 1.0 (June 16, 2006)
Initial release.

Version 1.1 (September 24, 2006)
#23 - Fixed warning in control panel.

Download

No longer available.