This plugin hasn’t been updated in over 2 years. It may no longer be maintained or supported and may have compatibility issues when used with more recent versions of WordPress.

MetaCAPTCHA

Description

MetaCaptcha uses the proof-of-work (or “client puzzle”) approach for combating spam. Proof-of-work approaches slow down spammers by requiring them to solve computational puzzles before accessing a desired service. The idea is to impose a per-access cost in hopes of reducing abuse. More specifically, the cost to spammers will be computational resources that they devote to solving a puzzle before sending each message. The approach was first outlined by Dwork and Naor. However, Laurie and Clayton demonstrated that a small constant cost would fail to significantly reduce spam and a large one would burden legitimate users. Later, Liu and Camp demonstrated that if puzzle difficulties were based on user reputations then a proof-of-work approach would indeed be successful. Thus, malicious clients (spammers) would need to be issued “harder” (longer to solve) puzzles than non- malicious clients. The new comments on your blog will be sent to our MetaCAPTCHA server for spam classification.

Installation

  1. Upload folder metacaptcha to the /wp-content/plugins/ directory
  2. Activate the plugin through the ‘Plugins’ menu in WordPress
  3. Register an account at http://www.metacaptcha.com/metacaptcha/documentation/registration/ and get the PRIVATE_KEY and PUBLIC_ID. Replace your PRIVATE_KEY and PUBLIC_ID at line 3 and 4 of metacaptcha_lib.php
  4. Done

Contributors & Developers

“MetaCAPTCHA” is open source software. The following people have contributed to this plugin.

Translate “MetaCAPTCHA” into your language.

Interested in development?

Browse the code, check out the SVN repository, or subscribe to the development log by RSS.

Changelog

2.3

  • Add useful computation fishy
  • Add exchange shared secret key

2.2

  • Fix readme.txt

2.1

  • Fix readme.txt
  • Simplify the cookies model
  • Storing local score and timestamp

2.0

  • Update code so it can work with MetaCAPTCHA protocol located on rabbit.cs.pdx.edu
  • Reload page after verifying cookies complete