So the first CAPTCHA system with the images was not user-friendly.

This time I think I will stick to a text-based system. It will pose simple arithmetic word questions. For example, "If you have 617 beans and a cowboy appears and gives you two more beans, how many beans do you have?"

The only problem with such a system is it is weak, due to the speed at which computers can generate numbers to try.

I can increase the strength of the system by adding another question. I still want to do something with images. So I think I'll have a little generated image of a box and a circle. Then I'll ask if the circle is inside the box.

And to top it off, I'll only allow five attempts from the same IP address within the space of an hour.

A bit complicated and probably not that well thought out, but it gives me something to do.

There are so many things that need to be done with this blogging platform. Several functions are still in the state the bake script left them. And I want to add more stuff.

• Drafts
• Stuff on the right-hand column
• Search function
• Enhanced user profiles
• Etc.

And for that I have decided I need a CAPTCHA.

I could use PHP's GD library to create your standard distorted-text-on-busy-background CAPTCHA, but I want to try something else.

I am thinking of a row of simple images--squares, triangles and circles. I will generate the images with GD so the file names are the same. Let's say there will be 20 images in the row.

I will generate some instructions tell the user which six images to use. The candidate user will then have to type in the color and shape of those six images. I will only have four colors and three shapes, so the users will abbreviate. For instance, a red square would be 'rs'.

That allows for 4^6*3^6 = 2985984 combinations, which would be good enough for my site. And with a little help from IP logging, it would probably be good enough for any site.

Here's a mockup:

colors:	shapes
red = r blue = b green = g yellow = y	circle = c square = s triangle = t

Please enter the first letter of the color followed by the first letter of the shape for pictures: 8, 3, 9, 10, 17, and 12 Enter them in the order specified.

Update: I had my brother test this out. It sucks. I'll come up with something simpler.