Simple Captcha Solution

Simple Captcha Solution for protecting web forms from non-human submissions. This is how the image might look like:
(click the image for source code)
It looks different every time you reload the page. It can be customized.

Build the method for processing the submission:

protected void Submit_Click(object sender, EventArgs e)
{
	if (Page.IsValid)
	{
		// your code here
	}
}

Put the validator event into code:

protected void CaptchaValidator_ServerValidate(object source, ServerValidateEventArgs args)
{
	args.IsValid = captcha.Text.Equals((string)Session["captcha"], StringComparison.OrdinalIgnoreCase);
}

Put the image and input box on the page:

<img runat="server" alt="captcha" align="left" src="~/captcha.aspx" />
<asp:TextBox ID="captcha" runat="server" Width="80" />

Put validators on the page:

<asp:RequiredFieldValidator runat="server" ErrorMessage="*" ControlToValidate="captcha" />
<asp:CustomValidator runat="server" ErrorMessage="*" ControlToValidate="captcha" OnServerValidate="CaptchaValidator_ServerValidate" />

Add the Captcha Image Generator page to your site.