Simple CAPTCHA Twist

[NinjaNoodles]

This a fairly simple trick to fool most SPAM bots:

On your CAPTCHA image, put text on the default graphic (that is, the graphic before text is dynamically added). Then, generate your actual CAPTCHA key in a different color...

Example: 14po7df2g

Tell the user to enter only the black text, and they're in. :)

For added security, you could dynamically generate the "decoy" text as well.

[mariush]

You can also a div with the background set as an image, under the actual captcha the background is transparent and right after the text, a text continues inside the image.

User would have to enter the complete number.
In the end if someone really wants to automate it, yours is actually simple to do.

See the example here (http://dev.helpedia.com/dp/test.html)

[Cesay]

From what I've been told, using color to differentiate between items on a web page is not a good idea because many people are color blind.

[NinjaNoodles]

There are simulators to show you if your colors work for everyone.

Or you could just do it by font, underline, etc.

[rodney88]

You want to improve a CAPTCHA by making it even less accessible?

Sure, red-green colour blindness is the most common and maybe they can still use it but there are loads of different types all the way down to complete monochromacy. Even assuming perfect vision, I'm using a fairly old screen atm and with the sun shining onto it, it's very difficult to see the difference in colour just in the example you posted.

You're also assuming everyone will both read and understand the instructions. I usually go into autopilot when filling out a form - and I'm sure most people have completed enough CAPTCHAs to see a textfield next to an image of distorted text and automatically type in what they see and move on, without bothering or needing to read the instructions.

[NinjaNoodles]

There are simulators to show you if your colors work for everyone.

Or you could just do it by font, underline, etc.

See above.

[rodney88]

Yes, I know that's what you said - it was such a ridiculous post I had to reply to it.

But apparently you're only interested in positive feedback, so er, yeh. Good luck.

[NinjaNoodles]

Well then, why not a choice of multiple words, numbers or strings, one with a circle around it?

I'm simply presenting the concept.

[ProgrammersTalk]

http://www.programmerstalk.net/thread695.html

may be helpful to you. It's a complete tutorial on how to make CAPTCHA with PHP :)

[NinjaNoodles]

I've already made one - with a static M on the right, and it's never let a SPAM bot by.