Check Password case sensitive in Asp.net using Sql server during Login

Intoduction: In this article I will explain how we can check password sensitivity in asp.net using sql server during login.

Description:

In the last article i have explained How to Create registration form in Asp.net,How to Create Login Form in Asp.net OR Login Form with Check Username and Password aviabilty in Asp.net and How to Recover Forgot Password via Email in Asp.net.

Case sensitive password are not easy to crack and increase the security level.

Example:

 I created a Table USER_REGISTRATION:

ID	int
USERNAME	varchar(50)
PASSWORD	varchar(50)
FIRST_NAME	varchar(50)
LAST_NAME	varchar(50)
SEX	varchar(50)
EMAIL_ID	varchar(50)

Here ID is autoincrement and primary key.

Design the .aspx page shown below:

<table align="center">

    <tr><td>Username:-</td><td>

        <asp:TextBox ID="txtusername" runat="server"></asp:TextBox></td></tr>

        <tr><td>&nbsp;</td></tr>

        <tr><td>Password:-</td><td>

            <asp:TextBox ID="txtpassword" TextMode="Password" runat="server"></asp:TextBox></td></tr>

            <tr><td>&nbsp;</td><td>

                <asp:Button ID="btnlogin" runat="server" Text="Login"

                    onclick="btnlogin_Click" /></td></tr>

                    <tr><td>Forget Password?</td><td>

                        <asp:LinkButton ID="LinkButton1" runat="server" >Click Here</asp:LinkButton></td></tr>

                </table>

After that write the below given code on button click (.aspx.cs):

using System.Data;

using System.Data.SqlClient;

using System.Configuration;

SqlConnection con = new SqlConnection(ConfigurationManager.ConnectionStrings["Connection"].ToString());

protected void btnlogin_Click(object sender, EventArgs e)

    {

        try

        {

            if(checknullvalidation() == false)

            {

                return;

            }

            string query = "Select * from USER_REGISTRATION where USERNAME = @USERNAME and PASSWORD COLLATE Latin1_general_CS_AS = @PASSWORD";

            //To Check User And Password Case Sensitivity

            // string query = "Select * from USER_REGISTRATION where USERNAME COLLATE Latin1_general_CS_AS = @USERNAME and PASSWORD COLLATE Latin1_general_CS_AS = @PASSWORD";

            SqlCommand cmd = new SqlCommand(query,con);

            con.Open();

            cmd.Parameters.AddWithValue("@USERNAME", txtusername.Text.Trim());

            cmd.Parameters.AddWithValue("@PASSWORD", txtpassword.Text);

            SqlDataAdapter adp = new SqlDataAdapter(cmd);

            DataTable dt = new DataTable();

            adp.Fill(dt);         

            if (dt.Rows.Count > 0)

            {

                //session for user

                Session["USERNAME"] = txtusername.Text;

                Response.Redirect("Welcome.aspx");

                con.Close();

            }

            else

            {               

                ClientScript.RegisterStartupScript(Page.GetType(), "validation", "<script language='javascript'>alert('Username/Password Doesn,t Match')</script>");

            }

        }

        catch(Exception ex)

        {

        }

    }

    //Check Validation

    public bool checknullvalidation()

    {

        if (txtusername.Text.Trim() == string.Empty)

        {

            Messagebox("Please enter username");

            txtusername.Focus();

            return false;

        }

        if (txtpassword.Text.Trim() == string.Empty)

        {

            Messagebox("Please enter your password");

            txtpassword.Focus();

            return false;

        }

        return true;

    }

    //Show Message

    private void Messagebox(string Message)

    {

        Label lblMessageBox = new Label();

        lblMessageBox.Text =

            "<script language='javascript'>" + Environment.NewLine +

            "window.alert('" + Message + "')</script>";

        Page.Controls.Add(lblMessageBox);

    }

In VB (.aspx.vb)

Imports System.Data

Imports System.Data.SqlClient

Imports System.Configuration

Dim con As New SqlConnection(ConfigurationManager.ConnectionStrings("Connection").ToString())

    Protected Sub btnlogin_Click(sender As Object, e As System.EventArgs) Handles btnlogin.Click

        Try

            If checknullvalidation() = False Then

                Return

            End If

            Dim query As String = "Select * from USER_REGISTRATION where USERNAME = @USERNAME and PASSWORD COLLATE Latin1_general_CS_AS = @PASSWORD"

            'To Check User And Password Case Sensitivity

            ' Dim query As String = "Select * from USER_REGISTRATION where USERNAME COLLATE Latin1_general_CS_AS = @USERNAME and PASSWORD COLLATE Latin1_general_CS_AS = @PASSWORD"

            Dim cmd As New SqlCommand(query, con)

            con.Open()

            cmd.Parameters.AddWithValue("@USERNAME", txtusername.Text.Trim())

            cmd.Parameters.AddWithValue("@PASSWORD", txtpassword.Text)

            Dim adp As New SqlDataAdapter(cmd)

            Dim dt As New DataTable()

            adp.Fill(dt)

            If dt.Rows.Count > 0 Then

                'session for user

                Session("USERNAME") = txtusername.Text

                Response.Redirect("Welcome.aspx")

                con.Close()

            Else

                ClientScript.RegisterStartupScript(Page.[GetType](), "validation", "<script language='javascript'>alert('Username/Password Doesn,t Match')</script>")

            End If

        Catch ex As Exception

        End Try

    End Sub

    'Check Validation

    Public Function checknullvalidation() As Boolean

        If txtusername.Text.Trim() = String.Empty Then

            Messagebox("Please enter username")

            txtusername.Focus()

            Return False

        End If

        If txtpassword.Text.Trim() = String.Empty Then

            Messagebox("Please enter your password")

            txtpassword.Focus()

            Return False

        End If

        Return True

    End Function

    'Show Message

    Private Sub Messagebox(Message As String)

        Dim lblMessageBox As New Label()

        lblMessageBox.Text = "<script language='javascript'>" + Environment.NewLine & "window.alert('" & Message & "')</script>"

        Page.Controls.Add(lblMessageBox)

    End Sub

Run the project and check the result.