Emacs Lisp reCAPTCHA library ¶

This library allows interaction with Google’s reCAPTCHA service

• reCAPTCHA: verifies that the user as correctly introduced the CAPTCHA.
• reCAPTCHA mailhide: used to encrypt email addresses in webpages, and decrypt them after a successful CAPTCHA.

The main entry points are:

• recaptcha-html: outputs the HTML code that needs to be included in a webpage to display the CAPTCHA.
• recaptcha-verify: takes as input the challenge (i.e. what the user wrote) and validates the CAPTCHA.
• recaptcha-mailhide-html: outputs the HTML to show an email address.

It was written primarily to be used with Elnode, a non-blocking webserver written in Emacs Lisp:

;; The following code can be used to quickly test the code, it is
;; based on elnode (and thus requires it of course). After evaluating
;; it http://localhost:8009/recaptcha and http://localhost:8009/mailhide/
;; are listening, each testing a particular functionality.
;;
;; (defun root-handler (httpcon)
;;   (elnode-hostpath-dispatcher httpcon
                                 '(("^.*//recaptcha/\\(.*\\)" . recaptcha-handler)
;; 				("^.*//mailhide/\\(.*\\)" . mailhide-handler))))
;;
;; (elnode-start 'root-handler :port 8009)

For the code, go to the GitHub repository.