So I found this article on CodeProject regarding simple captcha's. The next step was to create a webgui control derived from PictureBox that implement a IGatewayControl.
In short the important part is implementing GetGatewayHandler interface
IGatewayHandler IGatewayControl.GetGatewayHandler(IContext objContext, string strAction)
{
CaptchaImage img = new CaptchaImage(this.Text, this.Width, this.Height);
img.Image.Save(HttpContext.Current.Response.OutputStream, System.Drawing.Imaging.ImageFormat.Jpeg);
return null;
}
This will show an scrambled image of the controls Text property in the control.
For more information on this article see it on CodeProject here
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