Class wwWebMathCaptcha

A Captcha like control meant to verify that a human is posting to this link rather than an automated bot. Use on publically accessible forms that aren't secured behind authentication.

This control uses a simple math expression instead of an image to verify a human is accessing a form.

The control asks for a simple math expression using addition and multiplication to provide validation. The control renders the expression. User input can be validated on the server using the IsValidated property when the form is submitted.

To use and embed the control into a page::

<ww:wwwebmathcaptcha id="Captcha" runat="server" 
      MaxMathNumber="5" />

To check for a valid response in user code - like a Save button click:

IF (<<b>>!this.Captcha.IsValidated<</b>>)
   this.AddBindingError("Invalid validation.","Captcha_Input")


Using a non-image control is less resource intensive as no dynamic image creation request has to be fired against the server. This reduces overhead. Image captures are also increasingly under attack by spam bots and many simpler captchas (like the wwWebCaptcha control's images) are machine solvable these days using sophisticated OCR scanning. Using random expressions tend to be more difficult to automate and are easily foiled by moving things around in the expression display. It's also much less standard so often spam bots ignore these links.

Class Members

See also:

Class wwWebMathCaptcha

© West Wind Technologies, 1996-2018 • Updated: 01/20/14
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