Vincent Massol Think Tank - Fighting blog spam with captchas

Fighting blog spam with captchas

[ vmassol ] 20:22, Tuesday, 10 February 2004

I've just learnt that there was a name for "a computer-generated test that humans can pass but computer programs cannot". It's called a captcha. You can see those on some web sites during registration. Here's an example:

Some of my Octo workmates are developing a java framework for generating captchas called JCaptcha. What I find interesting is one possible use of captchas: preventing spam. More specifically the idea would be to use captchas to prevent blog spam. It means that people who enter blog comments would need to be humans. What I don't know is whether blog spam is being done manually by individuals or if it's automated. In any case this solution will prevent automated blog spam which is a good first step!

The JCaptcha project has just released a beta version. I guess one next step could be the creation of a MoveableType plugin. Then I would hope to convince Bob to let us try it on Codehaus blogs :-)

Update 18/04/04: It seems that James Seng beat me with this captcha idea. Not only the idea but also an MT implementation. In addition, he's created yet another MT plugin for preventing comment spam by implemeting an MT Bayesian filter.

It is a worthy idea but from my experience (I'm close to about 10 blogs and several mailing lists) - the problem isn't as much from bots as you might think.

I have seen listings on some of the job lists for "work at home placing ads on the internet" from several sources including some "development centers" in India. Unfortunately there is enough money in the porn, illicit drug and diet supplement industries to fund places where people will work for a few dollars a day to type ads into mailing lists, weblogs, and forums and other Internet based communication systems.

It is the next battleground of spam.

--MichaelD, February 16, 2004 06:18 PM

There are also reports that spammers have got around this by copying the images to porn servers and requiring those wanting access to decode the captcha. Then they can use the decoded word to automatically spam the original site. I almost feel like congratulating them on their lateral thinking...

--Chris Stevenson, February 24, 2004 06:19 AM

Nice article. I read an informative article about this recently in Communications of the ACM (Feb 2004). We might end up using JCaptcha on some of our projects here.

Thanks, Dafydd

--Dafydd Rees, March 15, 2004 08:53 PM

Hi Vincent

I was hoping you might be able to help me...

I have a role with a leading Brokerage in London - I am looking for a contract Developer who can extend Jira.

Can you advise me if you might be able to help me?

Thanks in advance

--Aisling , July 17, 2007 05:16 PM