Install-Package FreeSpire.PDF

using Spire.Pdf;

namespace EncryptPDF
{
    class Program
    {
        static void Main(string[] args)
        {
            // 加載 PDF
            PdfDocument pdf = new PdfDocument();
            pdf.LoadFromFile("示例.pdf");

            // 指定用戶密碼和所有者密碼
            string userPassword = "user123";
            string ownerPassword = "e-iceblue";

            PdfSecurityPolicy securityPolicy = new PdfPasswordSecurityPolicy(userPassword, ownerPassword);

            // 設(shè)置加密算法
            securityPolicy.EncryptionAlgorithm = PdfEncryptionAlgorithm.AES_256;

            // 設(shè)置文檔權(quán)限
            securityPolicy.DocumentPrivilege = PdfDocumentPrivilege.AllowAll;
            securityPolicy.DocumentPrivilege.AllowPrint = false; // 禁止打印
            securityPolicy.DocumentPrivilege.AllowContentCopying = false; // 禁止復(fù)制

            // 加密 PDF 并保存
            pdf.Encrypt(securityPolicy);
            pdf.SaveToFile("加密PDF.pdf", FileFormat.PDF);
        }
    }
}

  using Spire.Pdf.Security;

try
{
    PdfDocument doc = new PdfDocument();
    doc.LoadFromFile("input.pdf");
    
    //?重點(diǎn)提示：商業(yè)版功能
    PdfSecurity security = doc.Security;
    security.KeySize = PdfEncryptionKeySize.Key128Bit; // 設(shè)置128位AES加密
    security.OwnerPassword = "admin@2024"; //權(quán)限密碼
    security.UserPassword = "user123"; //打開(kāi)密碼
    
    //權(quán)限控制參數(shù)設(shè)置
    security.Permissions = PdfPermissionsFlags.Print 
                         | PdfPermissionsFlags.CopyContent;
    
    doc.SaveToFile("encrypted.pdf");
}
catch(NotSupportedException ex) 
{
    Console.WriteLine("加密功能需要商業(yè)版授權(quán)");
}