Switching Google reCaptcha Version 1 from 2 - captcha

Question

I have successfully designed and implemented Google reCaptcha Version 2 but now my Manager wants that to be of version 1 with numbers to be entered and validated. Is there a way to switch from later to former i.e.- from 2 to 1. I am using following library for reCaptcha:
<script src='https://www.google.com/recaptcha/api.js'></script>
Update..
To implement Captcha inside form i am using following HTML..
<form class="contact_form" action="#" method="post" name="contact_form">
<div class="frm_row">
<label id="lblmsg" />
<div class="clear">
</div>
</div>
<div class="g-recaptcha" data-sitekey="6Lduiw8TAAAAAOZRYAWFUHgFw9_ny5K4-Ti94cY9"></div>
<div class="login-b">
<span class="button-l">
<input type="button" id="Captcha" name="Submit" value="Submit" />
</span>
<div class="clear"> </div>
</div>
</form>
As i need to get the Captcha inside the above form to Validate and get the response on button click but as now i am using <script src="http://www.google.com/recaptcha/api/challenge?k=6Lduiw8TAAAAAOZRYAWFUHgFw9_ny5K4-Ti94cY9"></script> , so not getting the Captcha inside the form ..Please help me to get that ..Also here is the Jquery Ajax code to send the request on Server side code..
$(document).ready(function () {
alert("hii1");
$('#Captcha').click(function () {
alert("Hii2");
if ($("#g-recaptcha-response").val()) {
alert("Hii3");
var responseValue = $("#g-recaptcha-response").val();
alert(responseValue);
$.ajax({
type: 'POST',
url: 'http://localhost:64132/ValidateCaptcha',
data: JSON.stringify({ "CaptchaResponse": responseValue }),
contentType: "application/json; charset=utf-8",
dataType: 'json', // Set response datatype as JSON
success: function (data) {
console.log(data);
if (data = true) {
$("#lblmsg").text("Validation Success!!");
} else {
$("#lblmsg").text("Oops!! Validation Failed!! Please Try Again");
}
},
error: function (XMLHttpRequest, textStatus, errorThrown) {
alert("Error");
}
});
}
});
});
Please help me ..Thanks..

Answer 1

You have to verify the reCaptcha at "http://www.google.com/recaptcha/api/verify" on Server side.
The parameters of this are:
privatekey: Your Private Key
remoteip: User's IP Address
challenge: Value of input[name=recaptcha_response_field]
response: Value of input[name=recaptcha_challenge_field]
Therefore, you have to post them on your server-side method like this:
cshtml file:
var recaptchaResponseField=$("input[name=recaptcha_response_field]").val();
var recaptchaChallengeField=$("input[name=recaptcha_challenge_field]").val();
// ajax block
$.ajax({
url: '/api/VerifyReCaptcha/', // your Server-side method
type: 'POST',
data: {
ipAddress: '#Request.ServerVariables["REMOTE_ADDR"]',
challengeField: recaptchaChallengeField,
responseField: recaptchaResponseField
},
dataType: 'text',
success: function (data) {
// Do something
},
Since you are using .NET so an example of C# code is as follows:
cs file:
using System.Net;
using System.Collections.Specialized;
[HttpPost]
public bool VerifyReCaptcha(string ipAddress, string challengeField, string responseField)
{
string result = "";
using (WebClient client = new WebClient())
{
byte[] response =
client.UploadValues("http://www.google.com/recaptcha/api/verify", new NameValueCollection()
{
{ "privatekey", "{Your private key}" },
{ "remoteip", ipAddress },
{ "challenge", challengeField },
{ "response", responseField },
});
result = System.Text.Encoding.UTF8.GetString(response);
}
return result.StartsWith("true");
}