Jcap (Captcha Validation Javascript)

***NOTICE (2008-01-22): Due to overwhelming controversy, the developer would like to place emphasis on the fact that this script's main purpose (in it's basic form) is primarily for experimentation. No developer (including this one) would ever recommend implementing client-side scripting for the protection of highly sensitive data.

***NOTICE (2008-01-15): Version 2.0 released! Version 1.0 is no longer supported but is still available.

***NOTICE (2006-01-10): The developer assumes no liability with this resource and it is provided as is. This script is referred to as a "security development" because it can provide some minimal level of security. While it does seem to be an effective elementary form of security the developer does not claim that it is an impenetrable solution and thus the developer does not recommend implementing it for the protection of highly sensitive data.

***NOTICE (2006-10-25): The developer would like to thank Neville White of White-Hot Design for compressing Jcap's CAPTCHA image library from 4.2 mb to 1.0 mb!

What is Jcap (Captcha Validation Javascript)?

Though Jcap (Captcha Validation Javascript) is not recommended for highly sensitive data, it is an advanced level script that can be easily embedded into various forms for experimentation and can be a start for other uses that could have greater security value. The concept of the Jcap (Captcha Validation Javascript) is that it is the javascript (client-side) answer to Gimpy, a program developed by and based on the logic of the CAPTCHA Project at Carnegie Mellon University in that it can successfully tell humans and machines apart by administering a simple test that most humans can pass and current machines cannot pass. More information on the CAPTCHA Project at Carnegie Mellon University is available on their official website.

How do I utilize Jcap (Captcha Validation Javascript)?

There are many ways to utilize the Jcap (Captcha Validation Javascript). To install Jcap (Captcha Validation Javascript) download and decompress the Jcap zip file which contains all the required files. Get Jcap (jcap.zip) - 737 kb. After decompressing the files to the desired directory on your server change the value of the variable "imgdir" in the Jcap Javscript to the directory where the unzipped Captcha images on your server are located (With the trailing slash). Next, change the value of the variable "jfldid" in the Jcap Javscript to to the id name of you word field ("uword" is named by default) and change the variable value for "jfldsz" to the desired size of your word field. Optionally, you can change the value of "jfldcls" function argument to your desired CSS class. You may also need to edit the html script src location for where the md5.js and jcap.js files on your server are located if you put them in a separate directory from your form. Finally you need to modify the form field (If you've never used forms before you can access more information about them at http://www.w3schools.com/html/html_forms.asp) input tag named "action" change it's value to the URL of the application on your server and its method ("get or post"). Example:

<form action ="www.yourdomain.com/cgi-bin/formmail.cgi" method="get" onsubmit="return jcap();">

It is also recommended that you modify your application (ie. cgi, asp...) and/or form field to require the value "uword" to ensure that jcap was implemented before the execution of your application. Example:

<input type="hidden" id="required" name="required" value="uword">

For your reference, you can see Jcap (Captcha Validation Javascript) in action on our contact page.

Can I get the complete Source code for Jcap (Captcha Validation Javascript) royalty free and use it?

You got it. All I ask is to give credit where it's due.

Jonathan Feaster
Archreality Design
http://www.archreality.com/