«
»

Text base CAPTCHA dead?

April 27th, 2008 by alacy

Lots of sites have CAPTCHA “Completely Automated Public Turing test to tell Computers and Humans Apart” those warped letters and numbers you have to enter to register at some web sites or post comments on blogs. A computerworld article describes how spammers have programs that can now defeate them. It only succeeds 8%-13% of the time. But when you have a bunch of computers trying that is good enough. So spam coming from Microsoft, Yahoo and Google mail accounts is climbing.

But a company has come up with a Image based version. They alter the color and contrast on different sections of pictures. Then make the user pick a caption for a picture that has been overlaid with lines. Currently they believe only humans will be able to succeed at both tasks.


This entry was posted on Sunday, April 27th, 2008 at 12:45 pm and is filed under General Tech. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.

4 Responses to “Text base CAPTCHA dead?”

  1. steve Says:
    April 28th, 2008 at 7:51 am

    I tried the Image Based Version and hated it. I hate captchas in general, but understand they are valuable.

    It’s funny — you read, “captchas don’t work” repeatedly. But major sites continue to use them. Yahoo, MSN, Google. I guess filtering 90% of robotic activity is of some value.

  2. alacy Says:
    April 28th, 2008 at 2:44 pm

    I dislike them as well. Now for years I have reading that various research groups had designed programs that could break text base captcha’s, and therefore text based captcha were dying. Then text captcha’s would get harder. In fact I have run across some recently that it took me two or three attempts before I could pass them.

    But as far as I know it was only recently that the spamers have actually started using text captcha breaking programs. So I guess we’ll have to wait and see if the text ones get harder or if image based ones start being used, or some combination.

  3. alacy Says:
    May 3rd, 2008 at 10:58 am

    Here is microsofts image based CAPTCHA
    http://research.microsoft.com/asirra/

    Can a program spot cats?

  4. alacy Says:
    May 3rd, 2008 at 11:00 am

    Here is microsofts image based CAPTCHA
    Looks like wordpress doesn’t like links with microsoft in them

    Add http to this ://research.microsoft.com/asirra/

    Can a program spot cats?