Text To Image

[IntegrityWebDev]

I have a client that wants to implement Captcha of some kind on a simple contact form. I have no access to the server other than FTP'ing up files created in a text editor.

I've found several examples online but all seem to have logic or code flaws (surely not operator error!) so I've decided since it just needs to be simple, I will add it myself...or so I thought!

I have found code here and there for CREATING a graphic from text but I'm a bit hazy on how to DISPLAY that graphic on my page.

Because some parts of the site are still wonky that are not related to this, I will basically be doing this in notepad so no way to add things to the App_Code folder etc.

Could someone help me out with a fairly simple example of displaying text as graphic on a page, both what would go in the code behind and on the actual page.

[mattglet]

Can you just implement ReCaptcha? I can't imagine why there's a need to reinvent the wheel.

[IntegrityWebDev]

Maybe I'm missing something but to do ReCaptcha with ASP.NET, I think you have to have a DLL installed on the server...or am I missing something?

I have the key and the JS to show the recaptcha, but I cannot figure out how to get the value of it into my codebehind.

[IntegrityWebDev]

I finally got the Captcha to work. Maybe I am missing something obvious but I couldn't find a clear example of getting this to work, except by using the DLL. I finally pieced it together. For the sake of completeness and posterity :-) I'm going to post what I did.

First I applied for my API key, used the global because i have 4 sites to use this on.

In the form/web page I added this code:

 <script type="text/javascript"
 src="http://www.google.com/recaptcha/api/challenge?k=mypublickey">
 </script>
 <noscript>
 <iframe src="http://www.google.com/recaptcha/api/noscript?k=mypublickey"
 height="250" width="500" frameborder="0"></iframe><br>
 <textarea name="x" rows="3" cols="40">
 </textarea>
 <input type="hidden" name="recaptcha_response_field"
 value="manual_challenge">
 </noscript>

Then in the button click I added this (right now it just sends the result back to a label but you could change as needed:

 string response1 = Request["recaptcha_response_field"];
 string challenge1 = Request["recaptcha_challenge_field"];
 string privatekey1 = "myprivatekey";
 string remoteip1 = Request.ServerVariables["REMOTE_ADDR"];

 Uri address = new Uri("http://www.google.com/recaptcha/api/verify");

 // Create the web request 
 HttpWebRequest request = WebRequest.Create(address) as HttpWebRequest;

 // Set type to POST 
 request.Method = "POST";
 request.ContentType = "application/x-www-form-urlencoded";

 // Create the data we want to send 
 StringBuilder data = new StringBuilder();
 data.Append("&response=" + HttpUtility.UrlEncode(response1));
 data.Append("&challenge=" + HttpUtility.UrlEncode(challenge1));
 data.Append("&privatekey=" + HttpUtility.UrlEncode(privatekey1));
 data.Append("&remoteip=" + HttpUtility.UrlEncode(remoteip1));

 // Create a byte array of the data we want to send 
 byte[] byteData = UTF8Encoding.UTF8.GetBytes(data.ToString());

 // Set the content length in the request headers 
 request.ContentLength = byteData.Length;

 // Write data 
 using (Stream postStream = request.GetRequestStream())
 {
 postStream.Write(byteData, 0, byteData.Length);
 }

 // Get response 
 using (HttpWebResponse response = request.GetResponse() as HttpWebResponse)
 {
 // Get the response stream 
 StreamReader reader = new StreamReader(response.GetResponseStream());

 // Console application output 
 Label1.Text = reader.ReadToEnd();
 } 

Of course replace mypublickey and mypricatekey with your keys. YMMV...hope it helps someone though!