How can Encrypt a pdf file?

show this C# code example encrypts a PDF file named Loan.pdf with a password value of OpenPassword. The master password is PermissionPassword. The secured PDF document is saved as a PDF file named EncryptLoan.pdf.

using System;

using System.Collections;

using System.ComponentModel;

using System.Data;

using System.IO ;

namespace PasswordEncryptPDF

{

	class Class1

	{

		[STAThread]

		static void Main(string[] args)

		{

			try

			{

				//Create an EncryptionServiceService client object

				EncryptionServiceService  encryptionClient = new EncryptionServiceService(); 

				encryptionClient.Credentials = new System.Net.NetworkCredential("administrator", "password");

				//Create a BLOB object to store the PDF document 

				BLOB inDoc = new BLOB();

				//Specify the PDF document to encrypt with a password

				string path = "C:\\Adobe\\Loan.pdf";

				FileStream fs = new FileStream(path, FileMode.Open);

				//Get the length of the file stream 

				int len = (int)fs.Length; 

				byte[] ByteArray=new byte[len];

				//Populate the byte array with the contents of the FileStream object

				fs.Read(ByteArray, 0, len);

				inDoc.binaryData = ByteArray; 

				//Create a PasswordEncryptionOptionSpec 

				//object that stores encryption run-time values

				PasswordEncryptionOptionSpec passSpec = new PasswordEncryptionOptionSpec();

				//Specify the PDF document resource to encrypt

				passSpec.encryptOption=PasswordEncryptionOption.ALL;

				//Specify the Acrobat version

				passSpec.compatability =  PasswordEncryptionCompatability.ACRO_7;

				//Specify the password values

				passSpec.documentOpenPassword = "OpenPassword";

				passSpec.permissionPassword = "PermissionPassword";

				//Encrypt the PDF document with a password

				BLOB outDoc = encryptionClient.encryptPDFUsingPassword(inDoc,passSpec); 

				//Populate a byte array with a BLOB data

				byte[] outByteArray=outDoc.binaryData; 

				//Create a new file that represents the encrypted PDF document

				string FILE_NAME = "C:\\Adobe\\EncryptLoan.pdf" ; 

				FileStream fs2 = new FileStream(FILE_NAME, FileMode.OpenOrCreate);

				//Create a BinaryWriter object

				BinaryWriter w = new BinaryWriter(fs2);

				w.Write(outByteArray);

				w.Close();

				fs2.Close();

			}

			catch (Exception ee)

			{

				Console.WriteLine(ee.Message);  

			}

		}

	}

}