WordPress.org

PHPEnkoder is a port of the excellent Hivelogic Enkoder to PHP and, more specifically, to WordPress. It is used to display text in a way that users can see and bots can't.

The encoding system is directly and unabashedly stolen from the BSD-licensed source of Hivelogic Enkoder, which works by randomly encoding a piece of text and sending to the browser self-evaluating Javascript that will generate the original text. This works in two ways: first, a bot must first have a fairly complete Javascript implementation (in particular, it must have eval); second, the decoding process can be made arbitrarily computationally intensive. This is similar to the idea of charging computational payments to send e-mail, only this is actually implemented.

By default, PHPEnkoder scrambles e-mails in plaintext and in mailto: links. It additionally provides a shortcode for manual scrambling, used like so: [enkode text="shown to non-JS browsers"]this will be scrambled[/enkode].