Spam Bots and CAPTCHAs

Once, browsing the server’s log file, I noticed a visit from Google. Someone mistyped the word “captcha” as “capcha”, and by accident I mistypes this word in a post too. Now I decided to look at the popularity of possible misspells.

* captcha — about 46,700,000
* capcha — about 579,000 (Google suggests the correct spelling.)
* captca — about 3,300 (Google suggests the correct spelling.)
* kaptcha — about 3,920 (the project name)
* kapcha — about 16,600 (the project name, not related to captchas)
* kaptca — about 228 (Mostly login names. Google suggest the correct spelling.)

According to Google, 1.2% of people misspell “captcha” as “capcha”. Other possible ways of misspell are not popular.

The second experiment was with Technorati. It returned 5,378 results for “captcha” and 86 results for “capcha”. Surprisingly, the percent grows: 1.6%.

I already wrote about The best CAPTCHA ever — it’s a simple, but impressive looking math expression. Use of a scientific CAPTCHA is taking off. Now you can see one on the registration page of the library of Moscow Institute of Physics and Technology:

Translation:

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Last week I wrote about the “Spamper” phpbb MOD that used SPAM posts against the spammer. As I mentioned, the idea died because too many people thought that it amounted to a Distributed Denial of Service Attack (DDOS). No one wanted the legal liability that could result from what I believed was a great idea.

Well, I got to thinking… Maybe Spamper was a bad implementation of a good idea. So, I took the idea one step further. What do you think of this?

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Every now and then a smart anti-SPAM solution comes along that’s actually worth taking a close look at. ReCAPTCHA™ is one of those tools.

Everyone who reads my blog already knows that standard CAPTCHA utilities have been hacked. And you already know that the best form-based anti-SPAM tools require a modicum of human intelligence to unlock the comments form and allow a comment to be posted.

And that’s why I’m so excited about ReCAPTCHA. Not only is it human intelligence-based, but it’s free as well. And to make it even better, if you use ReCAPTCHA, you’ll actually be helping to spread literacy around the world.

Here’s how it works:

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CAPTCHA or not CAPCTHA… Any anti-spam protection disturbs your visitors. But folks at HotCaptcha.com found a nice trick to compensate the irritating proof-you-are-a-human step. What they do?

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I already wrote about the CAPTCHA I like most. Just to repeat, here it is:

Recently I found a very nice collection, don’t miss it: Craziest Captchas on the Web.

It’s an old joke now, but anyway it worth repeating. And I really like this CAPTCHA:

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