Lazarus Pascal Requires Chilkat v11.7.0+

Find Out Whether a PDF Needs a Password Before Loading It

See more PDF Protection Examples

Demonstrates PreLoadCheck, which examines a PDF file without loading it and without any password. It reports whether the file is encrypted, by which method and algorithm, whether a password is needed to open it, and what its permissions are. An application uses it to decide whether to ask for a password, or which certificate it needs, before calling LoadFile. PreLoadCheckBd does the same for a PDF held in memory. Lazarus Pascal

program ChilkatDemo;

// Demonstrates using the Chilkat Pascal wrapper via the C bridge DLL.
// Builds as a console application under Lazarus (FPC) or Delphi.

{$IFDEF FPC}
  {$MODE DELPHI}
{$ENDIF}
{$APPTYPE CONSOLE}

uses
  {$IFDEF UNIX}
  cthreads,
  {$ENDIF}
  SysUtils,
  CkDllLoader,
  Chilkat.Pdf,
  Chilkat.JsonObject;

// ---------------------------------------------------------------------------

procedure RunDemo;
var
  success: Boolean;
  pdf: TPdf;
  info: TJsonObject;

begin
  success := False;

  //  This example requires the Chilkat API to have been previously unlocked.
  //  See Global Unlock Sample for sample code.

  //  The PDF used in this example is available at two_page_memo.pdf

  //  The PDF used in this example is available at encrypted_user_password.pdf

  //  The PDF used in this example is available at no_copy_permission.pdf

  pdf := TPdf.Create;
  info := TJsonObject.Create;

  //  A PDF that is not encrypted.  Nothing but "encrypted" is reported for it.
  success := pdf.PreLoadCheck('qa_data/pdf/two_page_memo.pdf',info);
  if (success = False) then
    begin
      WriteLn(pdf.LastErrorText);
      Exit;
    end;
  WriteLn('two_page_memo.pdf');
  WriteLn('  encrypted: ' + info.BoolOf('encrypted'));

  //  A PDF that needs a password to open.
  success := pdf.PreLoadCheck('qa_data/pdf/encrypted_user_password.pdf',info);
  if (success = False) then
    begin
      WriteLn(pdf.LastErrorText);
      Exit;
    end;
  WriteLn('encrypted_user_password.pdf');
  WriteLn('  encrypted: ' + info.BoolOf('encrypted'));
  WriteLn('  method: ' + info.StringOf('method'));
  WriteLn('  algorithm: ' + info.StringOf('algorithm'));
  WriteLn('  openPasswordRequired: ' + info.BoolOf('openPasswordRequired'));

  //  A PDF that opens without a password but is restricted.  The permissions are readable without
  //  any password.
  success := pdf.PreLoadCheck('qa_data/pdf/no_copy_permission.pdf',info);
  if (success = False) then
    begin
      WriteLn(pdf.LastErrorText);
      Exit;
    end;
  WriteLn('no_copy_permission.pdf');
  WriteLn('  encrypted: ' + info.BoolOf('encrypted'));
  WriteLn('  openPasswordRequired: ' + info.BoolOf('openPasswordRequired'));
  WriteLn('  may copy: ' + info.BoolOf('permissions.copy'));

  //  The typical use: ask for a password only when one is needed, then load.
  success := pdf.PreLoadCheck('qa_data/pdf/encrypted_user_password.pdf',info);
  if (success = False) then
    begin
      WriteLn(pdf.LastErrorText);
      Exit;
    end;
  if (info.BoolOf('openPasswordRequired') = True) then
    begin
      //  An application would prompt for the password here.
      pdf.UserPassword := 'secret';
    end;
  success := pdf.LoadFile('qa_data/pdf/encrypted_user_password.pdf');
  if (success = False) then
    begin
      WriteLn(pdf.LastErrorText);
      Exit;
    end;
  WriteLn('loaded, pages: ' + pdf.NumPages);

  //  Sample output:

  //  two_page_memo.pdf
  //    encrypted: False
  //  encrypted_user_password.pdf
  //    encrypted: True
  //    method: password
  //    algorithm: rc4-128
  //    openPasswordRequired: True
  //  no_copy_permission.pdf
  //    encrypted: True
  //    openPasswordRequired: False
  //    may copy: False
  //  loaded, pages: 1


  pdf.Free;
  info.Free;

end;

// ---------------------------------------------------------------------------

begin

  try
    RunDemo;
  except
    on E: Exception do
      WriteLn('Unhandled exception: ', E.ClassName, ': ', E.Message);
  end;

  WriteLn;
  {$IFDEF MSWINDOWS}
  WriteLn('Press Enter to exit...');
  ReadLn;
  {$ENDIF}
end.