Adding reCAPTCHA v2 to asp.net webpage

-- -- 877 Reputation points
2022-08-10T18:41:41.547+00:00

Hi

I have a simple asp.net webform which has the reCAPTCHA v2 code added to it. Web page code is below.

The reCAPTCHA v2 image appears OK.

How can I now block form submission if user fails reCAPTCHA v2?

Thanks

Regards 

<%@ Page Language="vb" AutoEventWireup="false" CodeBehind="Application.aspx.vb" Inherits="ApplicationForm.Application" %>  
<html>  
   <head>  
      <script>  
      function doSubmit(btnSubmit) {  
        if (typeof (Page_ClientValidate) == 'function' && Page_ClientValidate() == false)   
        {  
          return false;  
        }  
        btnSubmit.disabled = 'disabled';  
        btnSubmit.value = 'Processing. This may take a few moments...';  
        <%= ClientScript.GetPostBackEventReference(btnSubmit, string.Empty) %>;  
      }  
      </script>  
      <script src="https://www.google.com/recaptcha/api.js" async defer></script>  
   </head>  
   <body>  
         <form id="form1" runat="server" class="wpcf7">  
            <asp:TextBox ID="forename" runat="server" ></asp:TextBox>  
            <asp:TextBox ID="dob" runat="server" TextMode="Date"></asp:TextBox>  
            <asp:RequiredFieldValidator  id="abc" runat="server" ControlToValidate="dob" ErrorMessage="DOB missing"></asp:RequiredFieldValidator>  

            <asp:Button ID="btnSubmit" runat="server" Text="Send your details" OnClick="btnSubmit_Click" OnClientClick="doSubmit(this)" />  
  
            <div class="g-recaptcha" data-sitekey="MyreCAPTCHAv2SiteKeyHere"></div>  
         </form>  
   </body>  
</html>
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  1. XuDong Peng-MSFT 10,176 Reputation points Microsoft Vendor
    2022-08-16T02:13:04.293+00:00

    Hi @-- -- ,

    Based on your requirement, you can try to use its callback function to implement client-side validation and allow form submission based on this result. Simply refer to the following code samples:

    Page code: 

    <div id="dvCaptcha">  
</div>  
<asp:TextBox ID="txtCaptcha" runat="server" Style="display: none" />  
<asp:RequiredFieldValidator ID="rfvCaptcha" ErrorMessage="Captcha validation is required." ControlToValidate="txtCaptcha"  
    runat="server" ForeColor="Red" Display="Dynamic" />  
<br />  
<asp:Button ID="btnSubmit" Text="Submit" runat="server" />

    VB.NET code: 

    Partial Class Default  
    Inherits System.Web.UI.Page  
    Protected Shared ReCaptcha_Key As String = "<RECaptcha Site Key>"  
    Protected Shared ReCaptcha_Secret As String = "<RECaptcha Secret Key>"  
   
    <WebMethod()> _  
    Public Shared Function VerifyCaptcha(response As String) As String  
        Dim url As String = "https://www.google.com/recaptcha/api/siteverify?secret=" & ReCaptcha_Secret & "&response=" & response  
        Return (New WebClient()).DownloadString(url)  
    End Function  
End Class

    Script code:
    230225-image.png

    Best regards,
    Xudong Peng

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