保护pdf文件与密码c#

using System;
using System.IO;
using iTextSharp.text;
using iTextSharp.text.pdf;

public class PdfProtectionExample
{
    public static void ProtectPdfWithPassword(string inputFilePath, string outputFilePath, string userPassword, string ownerPassword)
    {
        PdfReader reader = new PdfReader(inputFilePath);
        using (FileStream fs = new FileStream(outputFilePath, FileMode.Create, FileAccess.Write, FileShare.None))
        {
            PdfStamper stamper = new PdfStamper(reader, fs);
            stamper.SetEncryption(
                userPassword: System.Text.Encoding.Default.GetBytes(userPassword),
                ownerPassword: System.Text.Encoding.Default.GetBytes(ownerPassword),
                permissions: PdfWriter.ALLOW_PRINTING,
                encryptionType: PdfWriter.STANDARD_ENCRYPTION_128
            );
            stamper.Close();
        }
        reader.Close();
    }

    public static void Main(string[] args)
    {
        string inputFilePath = "input.pdf";
        string outputFilePath = "output.pdf";
        string userPassword = "user123";
        string ownerPassword = "owner456";

        ProtectPdfWithPassword(inputFilePath, outputFilePath, userPassword, ownerPassword);
        Console.WriteLine("PDF file protected successfully.");
    }
}