NWA-PCUG Newsletter Article, October 2006
(Completely Automated Public Turing test
to tell Computers and Humans Apart)

By Sandy Berger. Compu-KISS
sandy@compukiss.com (click to email author)

Have you ever tried to sign up for a message board or Web service and been presented with an image with letters and numbers which you are asked to read and type into the Web form? While the shape, size, and background of the image varies it always has contains a series of letters and numbers, usually on a graphic background.

Often the letters and numbers are distorted and you have to struggle to recognize them, making you wonder why the website is making you go through this extra step. Don’t blame the website. This image-recognition routine is something caused by cousins of the nasty spammers who have permeated our email.

The mechanism that makes you type in this information is called a CAPTCHA. If you know what those letters stand for, you will have a pretty good idea of why this mechanism is being employed. CAPTCHA stands for Completely Automated Public Turing test to tell Computers and Humans Apart.

Here’s the story. Spammers have completely infiltrated the world of the Internet. In email they try to get you to buy their wares. On message boards they list links to their Viagra and pornographic websites so that they get better positioning in the search engines. They overload online opinion polls and they sign up for free email accounts which they use to send out more spam.

For the most part, all of this spam activity is done automatically. The spammers send out what we call “bots”. These are actually software programs that search the Internet and imitate the behavior of a human. These bots are smart enough to fill out registration forms and so they can automatically register at a variety of websites.

We recently had an attack of these automated bots on our Compu-KISS message boards. After years of being unaffected, we suddenly had hundreds of postings that told off-color jokes and lead to pornographic and drug-selling websites. We moved the website to a new area (http://www.happycomputing.com), but were still inundated by these automated posting. So we installed a CAPTCHA. Now when a new person registers for the message board they must type in the five letters and numbers that they see on the screen to prove that they are human. Since the CAPTCHA is a graphic image, most of the bots cannot read the text like humans can.

The CAPTCHA that we use has letters and numbers that are undistorted, so it is easy to use. If, however, we are attacked by some of the smarter bots that are out there, we will have to distort the letters and numbers slightly to make it even harder for the bots to register.

Although a slight inconvenience to the average user, the CAPTCHA is a real roadblock to vision impaired Internet users who use screen readers which, like the bots, are unable to read the text on the CAPTCHA.

It is extremely unfortunate that we all have to be inconvenienced because of the activities of Internet spammers. I really hated to have to install this software, but I had no other choice. The same is true of many other websites and Web services. So when you encounter a CAPTCHA, don’t blame the website, blame the spammers!

The Compu-KISS Message Boards can be accessed at http://www.compukiss.com or directly at http://www.happycomputing.com

Sandy Berger, The Compu-KISS® Lady…nationally respected computer authority, journalist, media guest, speaker, and author is a seasoned 30-year computer expert. Sandy is a consumer advocate promoting simplicity, ease-of-use, and stability in consumer technology products. She works with hardware and software developers to help them make their products more user-friendly.

There is no restriction against any non-profit group using this article as long as it is kept in context with proper credit given the author. The Editorial Committee of the Association of Personal Computer User Groups (APCUG), an international organization of which this group is a member, brings this article to you.

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