This plugin provides a shortcode that renders a form that allows you to enter a string of words and get keys back for each word. You can then put those keys back into the same form to get the words back out.
Please read this entry from Wikipedia.
NOTE: THIS IS NOT SECURE. THIS IS A TOY.
Usage
Please this shortcode anywhere you’d like: [cypher-form] . View the form. Enter a string of words, something like “this is cool” and choose Encypher and submit.