I thought I would post this here for anyone running a Domino web site on the public internet which allows web form submissions.  You can implement CAPTCHA in Domino web forms using simply Notes formula language. :)

 

CAPTCHA for Domino web forms - Security Image Generator
This article instructs Domino Developers how to add a CAPTCHA to a Domino web form.  Domino web applications running on the public internet are susceptible to spam data submission especially if the web form validation relies soley on JavaScript and the web site is not SSL enabled.
http://www.notesmail.com/home.nsf/tip20100506

 

Here's an example of a web site where it has been implemented if you would like to test it:  http://www.notesmail.com/downloads

FYI

A CAPTCHA (an acronym for "Completely Automated Public Turing test to tell Computers and Humans Apart") is a type of challenge-response test used in computing to determine whether or not the user is human.

CAPTCHAs are used to prevent bots or automated programs from using various types of computing services or collecting certain types of sensitive information. Applications include preventing bots from taking part in online polls, registering for free email accounts (which may then be used to send spam) and collecting email addresses. CAPTCHAs can prevent bot-generated spam by requiring that the (unrecognized) sender pass a CAPTCHA test before the email message is delivered, but the technology can also be exploited by spammers by impeding OCR detection of spam in images attached to email messages. CAPTCHAs have also been used to prevent people from using bots to assist with massive downloading of content from multimedia websites. They are used in online message boards and blog comments to prevent bots from posting spam links as a comment or message.

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