How to do the URL encryption/decryption C#?

Question

User-1148373670 posted

Hi All,

I want to do the URL encryption across the application. Please provide some common method to implement the URL encryption/Decryption in C#. How to generate the encryption key randomly for particular session to use for encryption and decryption.

As of now I am generation random encryption key using below code

private static Random random = new Random();
public static string RandomString(int length)
{
const string chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
return new string(Enumerable.Repeat(chars, length)
.Select(s => s[random.Next(s.Length)]).ToArray());
}

I am not able to keep the key for particular session. Please sombody provide the input on it ASAP.

Thanks in advance

Ambrish

Answer 1

User-644521530 posted

You may pass a session relative integer to the function, then you may have that.

Answer 2

User-1148373670 posted

Thanks for reply....

I have created class that inheriting IHttpModule. Inside the class method not able to get the session assigned value. can u pls help me how to get the value in this class.

public class MyClass : IHttpModule
{

void context_BeginRequest(object sender, EventArgs e)
{

//here i am not able to get the session value. Assigning the session value at click of login button.

}

}

Thanks

Answer 3

User-707554951 posted

Hi info2ambrish,
From your description, I suggest you could encrypt QueryString Parameter values using AES Algorithm  and pass it to another page;
The following  is an example, you could refer to it :
Page 1:

<table border="0" cellpadding="0" cellspacing="0">
    <tr>
        <td>
            Name:
        </td>
        <td>
            <asp:TextBox ID="txtName" runat="server" Text="Mudassar Khan" />
        </td>
    </tr>
    <tr>
        <td>
            Technology:
        </td>
        <td>
            <asp:DropDownList ID = "ddlTechnology" runat="server">
                <asp:ListItem Text="ASP.Net" Value = "ASP.Net" />
                <asp:ListItem Text="PHP" Value = "PHP" />
                <asp:ListItem Text="JSP" Value = "JSP" />
            </asp:DropDownList>
        </td>
    </tr>
</table>
<hr />
<asp:Button ID="Button1" Text="Submit" runat="server" OnClick = "Submit" />

Codebehind:

using System.IO;
using System.Text;
using System.Security.Cryptography;
protected void Submit(object sender, EventArgs e)
{
    string name = HttpUtility.UrlEncode(Encrypt(txtName.Text.Trim()));
    string technology = HttpUtility.UrlEncode(Encrypt(ddlTechnology.SelectedItem.Value));
    Response.Redirect(string.Format("~/CS2.aspx?name={0}&technology={1}", name, technology));
}
 
private string Encrypt(string clearText)
{
    string EncryptionKey = "MAKV2SPBNI99212";
    byte[] clearBytes = Encoding.Unicode.GetBytes(clearText);
    using (Aes encryptor = Aes.Create())
    {
        Rfc2898DeriveBytes pdb = new Rfc2898DeriveBytes(EncryptionKey, new byte[] { 0x49, 0x76, 0x61, 0x6e, 0x20, 0x4d, 0x65, 0x64, 0x76, 0x65, 0x64, 0x65, 0x76 });
        encryptor.Key = pdb.GetBytes(32);
        encryptor.IV = pdb.GetBytes(16);
        using (MemoryStream ms = new MemoryStream())
        {
            using (CryptoStream cs = new CryptoStream(ms, encryptor.CreateEncryptor(), CryptoStreamMode.Write))
            {
                cs.Write(clearBytes, 0, clearBytes.Length);
                cs.Close();
            }
            clearText = Convert.ToBase64String(ms.ToArray());
        }
    }
    return clearText;
}

Page 2:

<table border="0" cellpadding="0" cellspacing="0">
    <tr>
        <td>
            Name:
        </td>
        <td>
            <asp:Label ID="lblName" runat="server" Text="" />
        </td>
    </tr>
    <tr>
        <td>
            Technology:
        </td>
        <td>
            <asp:Label ID="lblTechnology" runat="server" Text="" />
        </td>
    </tr>
</table>

CodeBehind:

using System.IO;
using System.Text;
using System.Security.Cryptography;
protected void Page_Load(object sender, EventArgs e)
{
    if (!this.IsPostBack)
    {
        lblName.Text = Decrypt(HttpUtility.UrlDecode(Request.QueryString["name"]));
        lblTechnology.Text = Decrypt(HttpUtility.UrlDecode(Request.QueryString["technology"]));
    }
}
 
private string Decrypt(string cipherText)
{
    string EncryptionKey = "MAKV2SPBNI99212";
    cipherText = cipherText.Replace(" ", "+");
    byte[] cipherBytes = Convert.FromBase64String(cipherText);
    using (Aes encryptor = Aes.Create())
    {
        Rfc2898DeriveBytes pdb = new Rfc2898DeriveBytes(EncryptionKey, new byte[] { 0x49, 0x76, 0x61, 0x6e, 0x20, 0x4d, 0x65, 0x64, 0x76, 0x65, 0x64, 0x65, 0x76 });
        encryptor.Key = pdb.GetBytes(32);
        encryptor.IV = pdb.GetBytes(16);
        using (MemoryStream ms = new MemoryStream())
        {
            using (CryptoStream cs = new CryptoStream(ms, encryptor.CreateDecryptor(), CryptoStreamMode.Write))
            {
                cs.Write(cipherBytes, 0, cipherBytes.Length);
                cs.Close();
            }
            cipherText = Encoding.Unicode.GetString(ms.ToArray());
        }
    }
    return cipherText;
}

Best regards
Cathy

Answer 4

User-471420332 posted

Dear info2ambrish,

                    Below is best working example, you can follow.

http://www.aspsnippets.com/Articles/Encrypt-and-Decrypt-QueryString-Parameter-Values-in-ASPNet-using-C-and-VBNet.aspx

Thank you

Mazhar

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