title: Google reCAPTCHA Validation Issue (accepts anything including blank)
body: <p>I'm attempting to implement Google's reCAPTCHA on a Classic ASP site and am attempting to follow the guidelines outline here:
  <a href="https://developers.google.com/recaptcha/docs/asp" rel="nofollow">https://developers.google.com/recaptcha/docs/asp</a></p>
  
  <p>Following the instructions on that page, I've added this code to the top of the page that contains the form:</p>
  
  <pre><code> &lt;%
   recaptcha_challenge_field  = Request("recaptcha_challenge_field")
   recaptcha_response_field   = Request("recaptcha_response_field")
   recaptcha_public_key       = "&lt;font color=red&gt;your_public_key&lt;/font&gt;" ' your public key
   recaptcha_private_key      = "&lt;font color=red&gt;your_private_key&lt;/font&gt;" ' your private key
   ' returns the HTML for the widget
   function recaptcha_challenge_writer()
   recaptcha_challenge_writer = _
   "&lt;script type=""text/javascript""&gt;" &amp; _
   "var RecaptchaOptions = {" &amp; _
   "   theme : 'red'," &amp; _
   "   tabindex : 0" &amp; _
   "};" &amp; _
   "&lt;/script&gt;" &amp; _
   "&lt;script type=""text/javascript"" src=""http://www.google.com/recaptcha/api/challenge?k=" &amp; recaptcha_public_key &amp; """&gt;&lt;/script&gt;" &amp; _
   "&lt;noscript&gt;" &amp; _
     "&lt;iframe src=""http://www.google.com/recaptcha/api/noscript?k=" &amp; recaptcha_public_key &amp; """ frameborder=""1""&gt;&lt;/iframe&gt;&lt;br&gt;" &amp; _
       "&lt;textarea name=""recaptcha_challenge_field"" rows=""3""cols=""40""&gt;&lt;/textarea&gt;" &amp; _
       "&lt;input type=""hidden"" name=""recaptcha_response_field""value=""manual_challenge""&gt;" &amp; _
   "&lt;/noscript&gt;"
   end function
   ' returns "" if correct, otherwise it returns the error response
   function recaptcha_confirm(rechallenge,reresponse)
   Dim VarString
   VarString = _
           "privatekey=" &amp; recaptcha_private_key &amp; _
           "&amp;remoteip=" &amp; Request.ServerVariables("REMOTE_ADDR") &amp; _
           "&amp;challenge=" &amp; rechallenge &amp; _
           "&amp;response=" &amp; reresponse
   Dim objXmlHttp
   Set objXmlHttp = Server.CreateObject("Msxml2.ServerXMLHTTP")
   objXmlHttp.open "POST", "http://www.google.com/recaptcha/api/verify", False
   objXmlHttp.setRequestHeader "Content-Type", "application/x-www-form-urlencoded"
   objXmlHttp.send VarString
   Dim ResponseString
   ResponseString = split(objXmlHttp.responseText, vblf)
   Set objXmlHttp = Nothing
   if ResponseString(0) = "true" then
     'They answered correctly
      recaptcha_confirm = ""
   else
     'They answered incorrectly
      recaptcha_confirm = ResponseString(1)
   end if
   end function
   server_response = ""
   newCaptcha = True
   if (recaptcha_challenge_field &lt;&gt; "" or recaptcha_response_field &lt;&gt; "") then
     server_response = recaptcha_confirm(recaptcha_challenge_field, recaptcha_response_field)
     newCaptcha = False  
   end if
  </code></pre>
  
  <p>%></p>
  
  <p>Also per that page, I've added this code to the form itself to generate the reCAPTCHA widget:</p>
  
  <pre><code> &lt;% if server_response &lt;&gt; "" or newCaptcha then %&gt;
  
      &lt;% if newCaptcha = False then %&gt;
  
        &lt;!-- An error occurred --&gt;
        Wrong!
  
      &lt;% end if %&gt;
  
        &lt;%=recaptcha_challenge_writer()%&gt;
  
    &lt;% else %&gt;
  
      &lt;!-- The solution was correct --&gt;
      Correct!
  
    &lt;%end if%&gt;
  </code></pre>
  
  <p>I can get the CAPTCHA to display properly, but it isn't verifying - it will accept any answer including being left blank. I believe some of the code needs to be added to my script that actually handles the data, but am not sure which code or where to put it.</p>
  
  <p>I've tried moving portions of the above code that appear to be for validation purposes to the script that processes the responses and generates an e-mail, but have had no luck there either.</p>
  
  <p>The for page can be viewed here:
  <a href="http://www.onlyproforma.com/mktimg/landingPage_ResultsFirst4_CAPTCHA.asp" rel="nofollow">http://www.onlyproforma.com/mktimg/landingPage_ResultsFirst4_CAPTCHA.asp</a></p>
  
  <p>I am aware there are other options, but I would like to get this one working if possible.</p>
  
  <p>Any help is greatly appreciated.</p>