Simple Login Form Using MD5 Hash Algorithm

The hash algorithm is allowed to create larger number of data using the small number of data.

Step 1: Create a simple login form as in the following screenshot:



By using the following HTML code:

<asp:Table ID="Table1" runat="server" Width="418px" Height="209px">
    <asp:TableRow>
        <asp:TableCell>
            User Name
        </asp:TableCell>
        <asp:TableCell>
            <asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
        </asp:TableCell>
    </asp:TableRow>
    <asp:TableRow>
        <asp:TableCell>
            Password
        </asp:TableCell>
        <asp:TableCell>
            <asp:TextBox ID="TextBox2" runat="server" TextMode="Password"></asp:TextBox>
        </asp:TableCell>
    </asp:TableRow>
    <asp:TableRow>
        <asp:TableCell>
            <asp:Button ID="Button1" runat="server" Text="Sign Up" OnClick="Message_click" />
        </asp:TableCell>
        <asp:TableCell>
            <asp:Button ID="Button2" runat="server" Text="login" OnClick="login_click" />
        </asp:TableCell>
        <asp:TableCell>
            <asp:Label ID="Label1" runat="server" />
        </asp:TableCell>
    </asp:TableRow>
</asp:Table>

Step 2: Now create the Database table as in the following screenshot:


Step 3: After creating the table use the following coding in Sign up button to get user name and password:

    public void Message_click(object sender, EventArgs e)
    {
        string username = TextBox1.Text.ToString();
        String password = TextBox2.Text;
//Get the encrypt the password by using the class
        string pass = encryption(password);
        Label1.Text = pass;
//Check whether the UseName and password are Empty
        if (username.Length > 0 && password.Length > 0)
        {
//creating the connection string
string connection = ConfigurationManager.ConnectionStrings["DefaultConnection"].ToString();
            SqlConnection con = new SqlConnection(connection);
            String passwords = encryption(password);
            con.Open();
// Check whether the Username Found in the Existing DB
            String search = "SELECT * FROM UserAccount WHERE (UserName = '" + username + "');";
            SqlCommand cmds = new SqlCommand(search, con);
            SqlDataReader sqldrs = cmds.ExecuteReader();
            if (sqldrs.Read())
            {
                String passed = (string)sqldrs["Password"];
                Label1.Text = "Username Already Taken";
            }
            else
            {
                try
                {
// if the Username not found create the new user accound
                    string sql = "INSERT INTO UserAccount (UserName, Password) VALUES ('" + username + "','" + passwords + "');";
                    SqlCommand cmd = new SqlCommand(sql, con);
                    cmd.ExecuteNonQuery();
                    String Message = "saved Successfully";
                    Label1.Text = Message.ToString();
                    TextBox1.Text = "";
                    TextBox2.Text = "";
                    Response.Redirect("Default2.aspx");
                }
                catch (Exception ex)
                {
                    Label1.Text = ex.ToString();
                }
                con.Close();
            }
        }

        else
        {
            String Message = "Username or Password is empty";
            Label1.Text = Message.ToString();
        }
    }

Step 4: Now encrypt the password by using the following method.

    public string encryption(String password)
    {
        MD5CryptoServiceProvider md5 = new MD5CryptoServiceProvider();
        byte[] encrypt;
        UTF8Encoding encode = new UTF8Encoding();
//encrypt the given password string into Encrypted data
        encrypt = md5.ComputeHash(encode.GetBytes(password));
        StringBuilder encryptdata = new StringBuilder();
//Create a new string by using the encrypted data
        for (int i = 0; i < encrypt.Length; i++)
        {
            encryptdata.Append(encrypt[i].ToString());
        }
        return encryptdata.ToString();
    }

After inserting the values inside the DB it will be like the following:



In the above Database table the user name is given as it is but the password is in encrypted String format

Step 5: Now login by using already created username and password.



Add the following code in the Login button.

public void login_click(object sender, EventArgs e)
{
    String username = TextBox1.Text.ToString();
    String password = TextBox2.Text;
    string con = ConfigurationManager.ConnectionStrings["DefaultConnection"].ToString();
    SqlConnection connection = new SqlConnection(con);
    connection.Open();
ncrypt the given password
    string passwords = encryption(password);
    String query = "SELECT UserName, Password FROM UserAccount WHERE (UserName = '" + username + "') AND (Password = '"+passwords+"');";

        SqlCommand cmd = new SqlCommand(query, connection);
        SqlDataReader sqldr = cmd.ExecuteReader();
        if (sqldr.Read())
        {
                Response.Redirect("Default3.aspx");
        }
            else
            {
                Label1.Text = "User or password is in correct not found";

            }

    connection.Close();
}

If the Password is correct it will take us to the Default3.aspx page, else it will show a message in the following label box:



Decryption is not possible using MD5, so I have again converted the entered password and then checked the value with the database.