public void Create()
{
Response.ContentType = "image/gif";
CaptchaHelper helper = new CaptchaHelper();
Random r = new Random();
double d = r.NextDouble();
string text = FormsAuthentication.HashPasswordForStoringInConfigFile(d.ToString(), "SHA1");
string vcode = text.Substring(4, 5);
Session["CaptchaCode"] = vcode.ToLower();
Session.Timeout = 1;
Bitmap capthaBmp = helper.Generate(vcode);
capthaBmp.Save(Response.OutputStream, ImageFormat.Gif);
}
