Generate unique OTP in asp.net using C#, vb.net

In this article I am going to explain how to generate unique OTP (one time password) in asp.net

Description:

In the previous article I have explained How to find (get) the Last day ofPrevious, Current and Next month in Sql server and Simple steps to display datapoint labels outside a pie Chart in asp.net.

OTP stand for one time password. It is a password that is valid for only one login session or transaction. It is widely used by the banks for transactions. It can be numeric as well as alphanumerical.

Implementation:

Method (code) to generate the numeric OTP:

Add a webform to project. Drag and drop the required control from toolbox to webform. Below given html markup consist of button and label control.

HTML markup:

   <fieldset style="width:420px">

    <legend><strong>OTP Example</strong></legend>

     <table>

    <tr><td>Click to Generate OTP :</td><td>

        <asp:Button ID="Button1" runat="server" Text="Generate OTP"/></td></tr>

     <tr><td></td><td></td></tr>

      <tr id="idotp" runat="server" visible="false"><td><strong>OTP</strong> :</td><td>

          <asp:Label ID="lblotp" runat="server"></asp:Label></td></tr>

    </table>

    </fieldset>

Generate numeric OTP

On button click write the below given to generate OTP:

C# code:

protected void Button1_Click(object sender, EventArgs e)

    {

        GenerateOTP();

    }

    private void GenerateOTP()

    {

        try

        {

            int length = 6;

            string numbers = "0123456789";

            Random objrandom = new Random();

            string strrandom = string.Empty;

            int noofnumbers = length;

            for (int i = 0; i < noofnumbers; i++)

            {

                int temp = objrandom.Next(0, numbers.Length);

                strrandom += temp;

            }

            lblotp.Text = strrandom;

            idotp.Visible = true;

        }

        catch (Exception ex)

        {

        }

    }

VB.net Code:

Protected Sub Button1_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Button1.Click

        GenerateOTP()

    End Sub

    Private Sub GenerateOTP()

        Try

            Dim length As Integer = 6

            Dim numbers As String = "0123456789"

            Dim objrandom As New Random()

            Dim strrandom As String = String.Empty

            Dim noofnumbers As Integer = length

            For i As Integer = 0 To noofnumbers - 1

                Dim temp As Integer = objrandom.[Next](0, numbers.Length)

                strrandom += temp

            Next

            lblotp.Text = strrandom

            idotp.Visible = True

        Catch ex As Exception

        End Try

    End Sub

Method (code) to generate Alphanumeric OTP:

HTML Markup:

   <fieldset style="width:420px">

    <legend><strong>OTP Example</strong></legend>

     <table>

    <tr><td>Click to Generate OTP :</td><td>

        <asp:Button ID="Button1" runat="server" Text="Generate OTP"/></td></tr>

     <tr><td></td><td></td></tr>

      <tr id="idotp" runat="server" visible="false"><td><strong>OTP</strong> :</td><td>

          <asp:Label ID="lblotp" runat="server"></asp:Label></td></tr>

    </table>

    </fieldset>

Generate alphanumeric OTP:

Write the below given code on button click event to generate the alphanumeric OTP.

C# Code:

  protected void Button1_Click(object sender, EventArgs e)

    {

        GenerateOTP(10);

    }

 

  private void GenerateOTP(int length)

    {

        try

        {

            string numbers = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";           

            Random objrandom = new Random();

            string strrandom = string.Empty;

            string passwordString = "";

            string opt = "";

            int noofnumbers = length;

            for (int i = 0; i < noofnumbers; i++)

            {

                int temp = objrandom.Next(0, numbers.Length);

                passwordString = numbers.ToCharArray()[temp].ToString();

                strrandom += passwordString;

            }

            while (opt.IndexOf(passwordString) != -1) ;

            lblotp.Text = strrandom;

            idotp.Visible = true;

        }

        catch (Exception ex)

        {

        }

    }

VB.net Code: 

    Protected Sub Button1_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Button1.Click

        GenerateOTP(10)

    End Sub

  

 Private Sub GenerateOTP(ByVal length As Integer)

        Try

            Dim numbers As String = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"

            Dim objrandom As New Random()

            Dim strrandom As String = String.Empty

            Dim passwordString As String = ""

            Dim opt As String = ""

            Dim noofnumbers As Integer = length

            For i As Integer = 0 To noofnumbers - 1

                Dim temp As Integer = objrandom.[Next](0, numbers.Length)

                passwordString = numbers.ToCharArray()(temp).ToString()

                strrandom += passwordString

            Next

            While opt.IndexOf(passwordString) <> -1

            End While

            lblotp.Text = strrandom

            idotp.Visible = True

        Catch ex As Exception

        End Try

    End Sub 

Build the application and run. To test the working click on generate OTP button.

DEMO:

 In this article we have learn how to generate unique OTP in asp.net using C# and vb.net . I hope you enjoyed this article.