Wednesday, 14 February 2018

Implement Google RECaptcha Code with Example in ASP.Net

Google RECaptcha Code with Example in ASP.Net

Description:

In this example we explain that how to implement the Google RECaptcha code in Asp.Net.or how to create Google RECaptcha to validate the user in website in Asp.Net.or how to implement the I am not Robert Google RECaptcha in Web Application using Asp.Net.

Google RECaptcha generally validate the Captcha response on client side using its call back functions.so how can we implement Google RECaptcha in our website?

Before implement you have to follow the below link to get the Site key and Secret key of the Google RECaptcha.

Aspx:

<html>
<head>
<title>Google RECaptcha Code with Example in ASP.Net</title>
<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.8.3/jquery.min.js"></script>
<script type="text/javascript" src="https://www.google.com/recaptcha/api.js?onload=onloadCallback&render=explicit" async defer></script>
<script type="text/javascript">
    var onloadCallback = function () {
        grecaptcha.render('dv_GoogleRECaptcha', {
            'sitekey': '<%=ReCaptcha_Key %>',
            'callback': function (response) {
                $.ajax({
                    type: "POST",
                    url: "Employee.aspx/VerifyCaptcha",
                    data: "{response: '" + response + "'}",
                    contentType: "application/json; charset=utf-8",
                    dataType: "json",
                    success: function (r) {
                        var captchaResponse = jQuery.parseJSON(r.d);
                        if (captchaResponse.success) {
                            $("[id*=txt_GoogleRECaptcha]").val(captchaResponse.success);
                            $("[id*=rfvCaptcha]").hide();
                        } else {
                            $("[id*=txt_GoogleRECaptcha]").val("");
                            $("[id*=rfvCaptcha]").show();
                            var error = captchaResponse["error-codes"][0];
                            $("[id*=rfvCaptcha]").html("RECaptcha error. " + error);
                        }
                    }
                });
            }
        });
    };
</script>
</head>
<body>
<form id="form1" runat="server">
  <div id="dv_GoogleRECaptcha">
</div>
<asp:TextBox ID="txt_GoogleRECaptcha" runat="server" Style="display: none" />
<asp:RequiredFieldValidator ID = "rfvCaptcha" ErrorMessage="Captcha validation is required." ControlToValidate="txt_GoogleRECaptcha"
    runat="server" ForeColor = "Red" Display = "Dynamic" />
<br />
<br />
<asp:Button ID="btnSubmit" Text="Submit" runat="server" />
</form>
</body>
</html>

 Aspx.cs:

protected static string ReCaptcha_Key = "<RECaptcha Site Key>";
        protected static string ReCaptcha_Secret = "<RECaptcha Secret Key>";

        [WebMethod]
        public static string VerifyCaptcha(string response)
        {
            string url = "https://www.google.com/recaptcha/api/siteverify?secret=" + ReCaptcha_Secret + "&response=" + response;
            return (new WebClient()).DownloadString(url);
        }



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