Add more types of verification, slow it down with the triple derivs

[MayorUshanka]

I think users should get to "reroll" the dice once. (Or some tweakable param)

I also think some other little tests would be good, but still easily doable in the head, such as:

• 2d vector dot products
• 2d/3d vec addition
• 2x2 matrix addition
• 2x2 matrix determinants
• 1st antiderivative of simple polynomials. Which are all easily autogenerated.

Also, doing triple derivatives is tedious to do in ones head and stifles quick replies. This can be a good thing, but also bad. Perhaps make the degree of derivate a parameter?

[ballerburg9005]

If you have a look at the math-php library IQcaptcha uses, it readily supports a wide array of advanced math functions.

It would be very minimal effort to use integration, matrix or vector math in the captcha. You could then enable the different modes via one of the "data-" flags, and maybe even specify the general level of difficulty (1 to 3 for example).

It is one of those things I will probably do some time next.

Do you need this feature directly?

Triple derivates are actually easier .. since you can simply discard most of the polynomial.

Rerolling the dice is a good idea, but it can't be a free roll because of captcha cracking.