Crypt pdf (using PdfSharp library)

The code to crypt a pdf file:

 void Crypt(FileInfo fileSource,
FileInfo fileDestination, string password)

        {

            PdfDocument document =
PdfReader.Open(fileSource.Fullname);

            PdfSecuritySettings
securitySettings = document.SecuritySettings;

securitySettings.UserPassword = securitySettings.OwnerPassword =
password;

            // Restrict some rights.

securitySettings.PermitAccessibilityExtractContent = false;

securitySettings.PermitAnnotations = false;

securitySettings.PermitAssembleDocument = false;

securitySettings.PermitExtractContent = false;

securitySettings.PermitFormsFill = false;

securitySettings.PermitFullQualityPrint = false;

securitySettings.PermitModifyDocument = false;

securitySettings.PermitPrint = false;

// saving document

document.Save(fileDestination.Fullname);

        }

Reference on the PdfSharp official web site.