Encrypt and Decrypt Query String in asp.net

Introduction: In this article I have explain how we can Encrypt and Decrypt Query String in asp.net.

Description:

In the last article I have explained Create multiple Language website in Asp.net, Edit, Update and Delete in Gridview using three tier architecture in Asp.net using SqlHelper, How to Export Selected rows of Gridview to Excel, Word and PDF in Asp.net and Nested Gridview Example in Asp.net OR Gridview inside Gridview in asp.net.

Add a weform to project. Drag and drop the controls from Toolbox and desgin the .aspx page as given below:

<table align="center"><tr><td>Employee Name:</td><td><asp:TextBox ID="txtname" runat="server"></asp:TextBox>

        <asp:RequiredFieldValidator ID="rfvname" runat="server"

            ControlToValidate="txtname" ErrorMessage="Enter Employee Name"

            ForeColor="#FF3300"></asp:RequiredFieldValidator>

        </td></tr>

    <tr><td>&nbsp;</td><td> <asp:Button ID="btnSubmit" runat="server" Text="Submit"

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

    </table>    

On Button click write the below given code (.aspx.cs)

using System.Security.Cryptography;

using System.IO;

using System.Text;

protected void btnSubmit_Click(object sender, EventArgs e)

    {

        string query = EncryptQueryString(txtname.Text);

        Response.Redirect("Decrypt_QueryString.aspx?empname=" + query);

    }

    public string EncryptQueryString(string inputString)

    {

        MemoryStream memStream = null;

        try

        {

            byte[] key = { };

            byte[] IV = { 18, 52, 86, 120, 144, 171, 205, 239 };

            string encryptKey = "aXb2uy4z";

            key = Encoding.UTF8.GetBytes(encryptKey);

            byte[] byteInput = Encoding.UTF8.GetBytes(inputString);

            DESCryptoServiceProvider provider = new DESCryptoServiceProvider();

            memStream = new MemoryStream();

            ICryptoTransform transform = provider.CreateEncryptor(key, IV);

            CryptoStream cryptoStream = new CryptoStream(memStream, transform, CryptoStreamMode.Write);

            cryptoStream.Write(byteInput, 0, byteInput.Length);

            cryptoStream.FlushFinalBlock();

        }

        catch (Exception ex)

        {

            Response.Write(ex.Message);

        }

        return Convert.ToBase64String(memStream.ToArray());

    }

In VB (.aspx.vb)

Imports System.IO

Imports System.Text

Imports System.Security.Cryptography

Protected Sub btnSubmit_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnSubmit.Click

        Dim query As String = EncryptQueryString(txtname.Text)

        Response.Redirect("Decrypt_QueryString.aspx?empname=" & query)

    End Sub

    Public Function EncryptQueryString(ByVal inputString As String) As String

        Dim memStream As MemoryStream = Nothing

        Try

            Dim key As Byte() = {}

            Dim IV As Byte() = {18, 52, 86, 120, 144, 171, 205, 239}

            Dim encryptKey As String = "aXb2uy4z"

            key = Encoding.UTF8.GetBytes(encryptKey)

            Dim byteInput As Byte() = Encoding.UTF8.GetBytes(inputString)

            Dim provider As New DESCryptoServiceProvider()

            memStream = New MemoryStream()

            Dim transform As ICryptoTransform = provider.CreateEncryptor(key, IV)

            Dim cryptoStream As New CryptoStream(memStream, transform, CryptoStreamMode.Write)

            cryptoStream.Write(byteInput, 0, byteInput.Length)

            cryptoStream.FlushFinalBlock()

        Catch ex As Exception

            Response.Write(ex.Message)

        End Try

        Return Convert.ToBase64String(memStream.ToArray())

    End Function

Add a new webform to project. Here I keep its name Decrypt_QueryString.aspx, drag and drop the control from Toolbox and desgin the .aspx page as shown:

<table align="center"><tr><td>

       <asp:Label ID="lbl" runat="server" Text="Encrypted Employee Name:"

           Font-Bold="True"></asp:Label></td><td>

       <asp:Label ID="lblencry" runat="server" ForeColor="#FF3300" Font-Bold="True"

               Font-Italic="True"></asp:Label></td></tr>

   <tr><td>&nbsp;</td><td><asp:Button ID="btnSubmit" runat="server" Text="Decrypt Querystring"

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

            <tr><td><b>

                <asp:Label ID="Label1" runat="server" Text="Decrypted Employee Name:"></asp:Label></b></td><td>

                <asp:Label ID="lbldecry" runat="server" ForeColor="#009933" Font-Bold="True"

                    Font-Italic="True"></asp:Label></td></tr>

   </table>

Write the given code on .aspx.cs page:

using System.Security.Cryptography;

using System.IO;

using System.Text;

protected void Page_Load(object sender, EventArgs e)

    {

        if (Request.QueryString["empname"] != null)

        {

            lblencry.Text = (Request.QueryString["empname"]);

        }

        else

        {

            btnSubmit.Visible = false;

            lbldecry.Visible = false;

            Label1.Visible = false;

            lbl.Visible = false;

            lblencry.Text = "No Records";

        }

    }

    public string DecryptQueryString(string inputString)

    {

        MemoryStream memStream = null;

        try

        {

            byte[] key = { };

            byte[] IV = { 18, 52, 86, 120, 144, 171, 205, 239 };

            string encryptKey = "aXb2uy4z";

            key = Encoding.UTF8.GetBytes(encryptKey);

            byte[] byteInput = new byte[inputString.Length];

            byteInput = Convert.FromBase64String(inputString);

            DESCryptoServiceProvider provider = new DESCryptoServiceProvider();

            memStream = new MemoryStream();

            ICryptoTransform transform = provider.CreateDecryptor(key, IV);

            CryptoStream cryptoStream = new CryptoStream(memStream, transform, CryptoStreamMode.Write);

            cryptoStream.Write(byteInput, 0, byteInput.Length);

            cryptoStream.FlushFinalBlock();

        }

        catch (Exception ex)

        {

            Response.Write(ex.Message);

        }

        Encoding encoding1 = Encoding.UTF8;

        return encoding1.GetString(memStream.ToArray());

    }

    protected void btnSubmit_Click(object sender, EventArgs e)

    {

        string name= DecryptQueryString(Request.QueryString["empname"]);

       lbldecry.Text=(name);

       lblencry.Visible = false;

       lbl.Visible = false;

    }

In VB (.aspx.vb)

Imports System.IO

Imports System.Text

Imports System.Security.Cryptography

  Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load

        If Request.QueryString("empname") IsNot Nothing Then

            lblencry.Text = (Request.QueryString("empname"))

        Else

            btnSubmit.Visible = False

            lbldecry.Visible = False

            Label1.Visible = False

            lbl.Visible = False

            lblencry.Text = "No Records"

        End If

    End Sub

    Protected Sub btnSubmit_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnSubmit.Click

        Dim nameAs String = DecryptQueryString(Request.QueryString("empname"))

        lbldecry.Text = (name)

        lblencry.Visible = False

        lbl.Visible = False

    End Sub

  

    Public Function DecryptQueryString(ByVal inputString As String) As String

        Dim memStream As MemoryStream = Nothing

        Try

            Dim key As Byte() = {}

            Dim IV As Byte() = {18, 52, 86, 120, 144, 171, 205, 239}

            Dim encryptKey As String = "aXb2uy4z"

            key = Encoding.UTF8.GetBytes(encryptKey)

            Dim byteInput As Byte() = New Byte(inputString.Length - 1) {}

            byteInput = Convert.FromBase64String(inputString)

            Dim provider As New DESCryptoServiceProvider()

            memStream = New MemoryStream()

            Dim transform As ICryptoTransform = provider.CreateDecryptor(key, IV)

            Dim cryptoStream As New CryptoStream(memStream, transform, CryptoStreamMode.Write)

            cryptoStream.Write(byteInput, 0, byteInput.Length)

            cryptoStream.FlushFinalBlock()

        Catch ex As Exception

            Response.Write(ex.Message)

        End Try

        Dim encoding1 As Encoding = Encoding.UTF8

        Return encoding1.GetString(memStream.ToArray())

    End Function

Now run the project and check the result. If it helps you than submit your comment.

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