Save Password using Encoding, decoding and Hashing Techniques in ASP.NET

Introduction

Plain text change in unreadable format known as encoding. And reverse of it known as decoding. Change a plain text into cipher text using any key known as hashing. There are lots of techniques available in hashing.
Here we take a simple example of among. First we start from Encoding.

How to change plain text into cipher text (Unreadable format)

first of all, take a string variable, after that take a byte array, which size is equal to string Length. Look like

String str = "Hello World";
Byte [] encode = new Byte[str.Length];

Get Bytes of string value using getBytes( ) method of UTF8 encoding. Now, your code look like

encode = Encoding.UTF8.GetBytes(str);
Now, change encoded byte array into Base64String.

encodepwd = Convert.ToBase64String(encode); // here encodepwd is the string variable.
Store encoded password is stored in encodepwd variable.

How to Change cipher Text into Plain Text

First of all, encoded string convert into specified string format, which is equivalent 8-bit unsigned integer array using FromBase64String ( ) method. count number of characters using GetCharCount( ) of byte array like.
 byte[] todecode = Convert.FromBase64String(decryptpwd);
 int charcountvariable = decode.GetCharCount(todecode, 0, todecode.Length);
Decode sequence of byte into set of characters using GetChars( ) method.

 char[] decode_array = new char[charcountvariable];
        decode.GetChars(todecode, 0, todecode.Length,decode_array ,0);

Complete source code

 <form id="form1" runat="server">

    <div>

    

        <table style="width:100%;">

            <tr>

                <td class="style1">

                    UserName</td>

                <td>

                    <asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>

                </td>

                <td>

                    &nbsp;</td>

            </tr>

            <tr>

                <td class="style1">

                    Password</td>

                <td>

                    <asp:TextBox ID="TextBox2" runat="server"></asp:TextBox>

                </td>

                <td>

                    &nbsp;</td>

            </tr>

            <tr>

                <td class="style1">

                    &nbsp;</td>

                <td>

                    <asp:Button ID="Button1" runat="server" onclick="Button1_Click" Text="Save" />

                </td>

                <td>

                    &nbsp;</td>

            </tr>

        </table>

    

    </div>

    <asp:GridView ID="GridView1" runat="server" Caption="Encrypted Data">

    </asp:GridView>

    <br />

    <asp:GridView ID="GridView2" runat="server" Caption="Decrypted Data" 

        onrowdatabound="GridView2_RowDataBound">

    </asp:GridView>

    <br />

    </form>

Business Logic Code

using System;

using System.Collections.Generic;

using System.Linq;

using System.Web;

using System.Web.UI;

using System.Web.UI.WebControls;

using System.Data.SqlClient;

using System.Data;

using System.Configuration;

using System.Text;

public partial class _Default : System.Web.UI.Page

{

    SqlConnection con;

    SqlCommand cmd;

    public _Default()

    {

        con = new SqlConnection();

        con.ConnectionString = ConfigurationManager.ConnectionStrings["ConnectionString"].ToString();

        cmd = new SqlCommand();

    }

    protected void Page_Load(object sender, EventArgs e)

    {

        if (!Page.IsPostBack)

        {

            bindgridview1();

            bindgridview2();

            

        }

    }

    private void bindgridview2()

    {

        con.Open();

        cmd.CommandText = "select * from [user]";

        cmd.Connection = con;

        SqlDataAdapter da = new SqlDataAdapter(cmd);

        DataSet ds = new DataSet();

        da.Fill(ds);

        GridView2.DataSource = ds;

        GridView2.DataBind();

      

    }

    private void bindgridview1()

    {

        con.Open();

        cmd.CommandText = "select * from [user]";

        cmd.Connection = con;

        SqlDataAdapter da = new SqlDataAdapter(cmd);

        DataSet ds = new DataSet();

        da.Fill(ds);

        con.Close();

        GridView1.DataSource = ds;

        GridView1.DataBind();

        

        

    }

    protected void Button1_Click(object sender, EventArgs e)

    {

        string pwdtxt = encodepassword(TextBox2.Text);

        con.Open();

        cmd.CommandText = "insert into [user](userName,Password)values(@us,@pw)";

        cmd.Parameters.AddWithValue("@us", TextBox1.Text);

        cmd.Parameters.AddWithValue("@pw", pwdtxt);

        cmd.Connection = con;

        cmd.ExecuteNonQuery();

        con.Close();

        bindgridview1();

        bindgridview2();

    }

    private string encodepassword(string p)

    {

        string encodepwd = string.Empty;

        byte[] encode = new byte[p.Length];

        encode = Encoding.UTF8.GetBytes(p);

        encodepwd = Convert.ToBase64String(encode);

        return encodepwd;

    }

    protected void GridView2_RowDataBound(object sender, GridViewRowEventArgs e)

    {

        if (e.Row .RowType ==DataControlRowType .DataRow)

        {

            string decryptpwd = e.Row.Cells[2].Text;

            e.Row.Cells[2].Text = decryptpassword(decryptpwd);

        }

        

    }

    private string decryptpassword(string decryptpwd)

    {

        string decryptpass = string.Empty;

        UTF8Encoding encode = new UTF8Encoding();

        Decoder decode = encode.GetDecoder();

        byte[] todecode = Convert.FromBase64String(decryptpwd);

        int charcountvariable = decode.GetCharCount(todecode, 0, todecode.Length);

        char[] decode_array = new char[charcountvariable];

        decode.GetChars(todecode, 0, todecode.Length,decode_array ,0);

        decryptpass = new String(decode_array);

        return decryptpass;

       

    }

    

}

Code Generate the following output

MD5 Hashing Example

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Data.SqlClient;
using System.Data;
using System.Configuration;
using System.Text;
using System.Security.Cryptography;

public partial class _Default : System.Web.UI.Page
{
    SqlConnection con;
    SqlCommand cmd;

    public _Default()
    {
        con = new SqlConnection();
        con.ConnectionString = ConfigurationManager.ConnectionStrings["ConnectionString"].ToString();
        cmd = new SqlCommand();


    }

    protected void Page_Load(object sender, EventArgs e)
    {
        if (!Page.IsPostBack)
        {
            bindgridview1();
           
            
        }

    }
    private void bindgridview1()
    {
        con.Open();
        cmd.CommandText = "select * from [user]";
        cmd.Connection = con;
        SqlDataAdapter da = new SqlDataAdapter(cmd);
        DataSet ds = new DataSet();
        da.Fill(ds);
        con.Close();
        GridView1.DataSource = ds;
        GridView1.DataBind();
        

        
    }
    protected void Button1_Click(object sender, EventArgs e)
    {
        string pwdtxt = getMd5Hash(TextBox2.Text);
        con.Open();
        cmd.CommandText = "insert into [user](userName,Password)values(@us,@pw)";
        cmd.Parameters.AddWithValue("@us", TextBox1.Text);
        cmd.Parameters.AddWithValue("@pw", pwdtxt);
        cmd.Connection = con;
        cmd.ExecuteNonQuery();
        con.Close();
        bindgridview1();
     


    }

    private static string getMd5Hash(string p)
    {
        MD5 md5Hasher = MD5.Create();

       
        byte[] data = md5Hasher.ComputeHash(Encoding.Default.GetBytes(p));

       
        StringBuilder sBuilder = new StringBuilder();

       
        for (int i = 0; i < data.Length; i++)
        {
            sBuilder.Append(data[i].ToString("x2"));
        }

      
        return sBuilder.ToString();

    }
  
}

Code Generate the following output