How to encrypt and decrypt xml file in asp.Net

Description:-

In this example we explain that how to encrypt and Decrypt XML file in asp.net with C#.in previous we already explain that how to Encrypt and Decrypt Password when user is register to website then it's password are stored in SqlServer database in Encrypt format and when user is login to website then it will fetch the Encrypt password from the database and Decrypt it and match with user enter password.
So this is simple thing but now in this example we will explain how to encrypt and Decrypt whole XML file in asp.net. The main advantages to Encrypt and Decrypt XML file is that even user cannotsee data in XML file because data are stored in Encrypt format so it cannot be read by any user.
When any operation is performed in XML file then it will first Decrypt XML file and then perform operation. So this is the best facility for any application for better security.

Default.aspx:-

<div>
  <asp:FileUpload ID="flupld_xmlfile" runat="server"/>
  <asp:Button ID="EncryptFileButton" runat="server" Text="Encrypt" onclick="EncryptFileButton_Click"/>
  <asp:Button ID="DecryptFileButton" runat="server" Text="Decrypt" onclick="DecryptFileButton_Click"/>
</div>

Default.aspx.cs:-

protected void Page_Load(object sender, EventArgs e) { }
protected void EncryptFileButton_Click(object sender, EventArgs e)
{
  //Get the Input File Name and Extension. 
  string fileName = Path.GetFileNameWithoutExtension(flupld_xmlfile.PostedFile.FileName);
  string fileExtension = Path.GetExtension(flupld_xmlfile.PostedFile.FileName);
  //Build the File Path for the original (input) and the encrypted (output) file. 
  string input = Server.MapPath("~/Files/") + fileName + fileExtension;
  string output = Server.MapPath("~/Files/") + fileName + "_enc" + fileExtension;
  //Save the Input File, Encrypt it and save the encrypted file in output path. 
  flupld_xmlfile.SaveAs(input);
  this.Encrypt(input, output);
  //Download the Encrypted File. 
  Response.ContentType = flupld_xmlfile.PostedFile.ContentType;
  Response.Clear();
  Response.AppendHeader("Content-Disposition", "attachment; filename=" + Path.GetFileName(output));
  Response.WriteFile(output);
  Response.Flush();
  //Delete the original (input) and the encrypted (output) file. 
  File.Delete(input);
  File.Delete(output);
  Response.End();
}

private void Encrypt(stringinputFilePath, stringoutputfilePath)
{
  stringEncryptionKey = "MAKV2SPBNI99212";
  using (Aesencryptor = Aes.Create())
  {
    Rfc2898DeriveBytespdb = newRfc2898DeriveBytes(EncryptionKey, newbyte[] { 0x49, 0x76, 0x61, 0x6e, 0x20, 0x4d, 0x65, 0x64, 0x76, 0x65, 0x64, 0x65, 0x76 });
    encryptor.Key = pdb.GetBytes(32); encryptor.IV = pdb.GetBytes(16);
    using (FileStreamfsOutput = newFileStream(outputfilePath, FileMode.Create))
    {
      using (CryptoStreamcs = newCryptoStream(fsOutput, encryptor.CreateEncryptor(), CryptoStreamMode.Write))
      {
        using (FileStreamfsInput = newFileStream(inputFilePath, FileMode.Open))
        {
          int data; while ((data = fsInput.ReadByte()) != -1)
          {
            cs.WriteByte((byte)data);
          }
        }
      }
    }
  }
}

protected void DecryptFileButton_Click(object sender, EventArgs e)
{
  //Get the Input File Name and Extension 
  string fileName = Path.GetFileNameWithoutExtension(flupld_xmlfile.PostedFile.FileName);
  string fileExtension = Path.GetExtension(flupld_xmlfile.PostedFile.FileName);
  //Build the File Path for the original (input) and the decrypted (output) file 
  string input = Server.MapPath("~/Files/") + fileName + fileExtension;
  string output = Server.MapPath("~/Files/") + fileName + "_dec" + fileExtension;
  //Save the Input File, Decrypt it and save the decrypted file in output path. 
  flupld_xmlfile.SaveAs(input);
  this.Decrypt(input, output);
  //Download the Decrypted File. 
  Response.Clear();
  Response.ContentType = flupld_xmlfile.PostedFile.ContentType;
  Response.AppendHeader("Content-Disposition", "attachment; filename=" + Path.GetFileName(output));
  Response.WriteFile(output);
  Response.Flush();
  //Delete the original (input) and the decrypted (output) file. 
  File.Delete(input);
  File.Delete(output);
  Response.End();
}

private void Decrypt(stringinputFilePath, stringoutputfilePath)
{
  string EncryptionKey = "MAKV2SPBNI99212";
  using (Aesencryptor = Aes.Create())
  {
    Rfc2898DeriveBytespdb = newRfc2898DeriveBytes(EncryptionKey, newbyte[] { 0x49, 0x76, 0x61, 0x6e, 0x20, 0x4d, 0x65, 0x64, 0x76, 0x65, 0x64, 0x65, 0x76 });
    encryptor.Key = pdb.GetBytes(32); encryptor.IV = pdb.GetBytes(16);
    using (FileStreamfsInput = newFileStream(inputFilePath, FileMode.Open))
    {
      using (CryptoStreamcs = newCryptoStream(fsInput, encryptor.CreateDecryptor(), CryptoStreamMode.Read))
      {
        using (FileStreamfsOutput = newFileStream(outputfilePath, FileMode.Create))
        {
          int data; 
          while ((data = cs.ReadByte()) != -1)
          {
            fsOutput.WriteByte((byte)data);
          }
        }
      }
    }
  }
}

Author : Umesh Patel

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