CAPTCHA图片认证的一些资料

在网站开发，为了区分是人输入的东西还是计算机自动输入的东西。经常用到CAPTCHA图片认证。

针对每种语言，有很多open source可以使用。

CAPTCHA

Python 

• PyCaptcha Python语言实现的CAPTCHA库
• Python Module at CAPTCHAs.net are providing a python module to simplify the task of writing a web application usingCAPTCHAs.net.

Java 

• The JCAPTCHA Project, java实现的Captcha库
• The reCAPTCHA Project, Java实现的库
• The simple CAPTCHA Project, a new open-source Java implementation.
• Proposal and source code for an audio based CAPTCHA written in Java.

PHP 

• VeriWord, PHP
• Image Verification Tutorial, PHP + GD(Planet Source Code)
• Image Verification, PHP + GD
• Auditor, PHP + GD
• Forms generation and validation class with a plug-in to implement a CAPTCHA validation input
• PEAR's Text_CAPTCHA, a PHP implementation.
• tEABAG_3D CAPTCHA, by OCR Research Team. 3D captchas using PHP4 + GD.
• Block AutoSubmit, Implementation that works with newer and older GD down to version 1.63.
• KCAPTCHA, PHP + GD, text-distortion.

Perl 

• Authen::CAPTCHA,Perl
• GD::SecurityImage, Perl(GD + Image::Magick).

Classic ASP 

• Poor man's CAPTCHA, aClassic ASP implementation using CSS, javascript and ASP.

.NET 

• CAPTCHA Image,.NET（ASP.NET用）
• CAPTCHA Custom Control, ASP.NET的CAPTCHA服务器控制板

Ruby 

• Ruby/CAPTCHA, Ruby和GD的Ruby实现的库

Smalltalk 

• SW2Captcha, aSmalltalk implementation using Morphic.

CAPTCHA服务

• CAPTCHA Service Free service, supports reload button, audio and smart captcha technology.
• captcha.jp , 日语版的CAPTCHA服务
• captchas.net, Free CAPTCHA Service (image and audio)
• address-protector.com, A way to avoid email spam; you give it your email address, it gives you a link which when clicked will show a captcha which when 'passed' will show your email address.

使用例子：

Here are the details of how to integrate Kaptcha into your own application.

• Put the appropriate .jar file (depending on which JDK you are using) into the WEB-INF/lib directory of your .war file.

• Put the image tag into your page (checking that the path to the .jpg matches up with what is defined in your web.xml below for the url-pattern):

<form action="submit.action">    <img src="kaptcha.jpg" /> <input type="text" name="kaptcha" value="" /></form>

• Put the reference in your web.xml (checking that the url-pattern path matches up with what you put in your html fragment above):

<servlet>        <servlet-name>Kaptcha</servlet-name>        <servlet-class>com.google.code.kaptcha.servlet.KaptchaServlet</servlet-class></servlet><servlet-mapping>        <servlet-name>Kaptcha</servlet-name>        <url-pattern>/kaptcha.jpg</url-pattern></servlet-mapping>

• In your code that manages the submit action:

String kaptchaExpected = (String)request.getSession()    .getAttribute(com.google.code.kaptcha.Constants.KAPTCHA_SESSION_KEY);String kaptchaReceived = request.getParameter("kaptcha");if (kaptchaReceived == null || !kaptchaReceived.equalsIgnoreCase(kaptchaExpected)){    setError("kaptcha", "Invalid validation code.");}

• Make sure to start your JDK with -Djava.awt.headless=true