Lazarus Pascal Requires Chilkat v11.7.0+

Password-Protect a PDF with AES-256 Encryption

See more PDF Protection Examples

Demonstrates the simplest way to encrypt a PDF so that it needs a password to open. The passwords come from the UserPassword and OwnerPassword properties, and Protection with the encrypt operation and an empty JSON uses the defaults: AES-256, everything encrypted, every permission granted. Protection only records the security the PDF will be saved with. Nothing is encrypted until WriteFile is called. 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;
  json: TJsonObject;
  jsonOut: TJsonObject;
  checker: TPdf;
  info: TJsonObject;
  reader: TPdf;

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

  pdf := TPdf.Create;
  success := pdf.LoadFile('qa_data/pdf/two_page_memo.pdf');
  if (success = False) then
    begin
      WriteLn(pdf.LastErrorText);
      Exit;
    end;

  //  The passwords are taken from these two properties at the time Protection is called.
  //  The user password opens the PDF.  The owner password opens it too, and is the one needed
  //  later to change or remove the protection.
  pdf.UserPassword := 'user-secret';
  pdf.OwnerPassword := 'owner-secret';

  //  An empty JSON asks for the defaults: AES-256, everything encrypted, every permission granted.
  json := TJsonObject.Create;
  jsonOut := TJsonObject.Create;
  success := pdf.Protection('encrypt',json,jsonOut);
  if (success = False) then
    begin
      WriteLn(pdf.LastErrorText);
      Exit;
    end;

  //  Nothing has been encrypted yet.  "pending" describes the security the PDF will be saved with.
  WriteLn('algorithm: ' + jsonOut.StringOf('pending.algorithm'));
  WriteLn('PDF version: ' + jsonOut.StringOf('pending.pdfVersion'));
  WriteLn('password needed to open: ' + jsonOut.BoolOf('pending.userPasswordRequired'));

  //  Writing the file applies it.
  success := pdf.WriteFile('qa_output/memo_encrypted.pdf');
  if (success = False) then
    begin
      WriteLn(pdf.LastErrorText);
      Exit;
    end;

  //  PreLoadCheck reports a file's encryption without loading it, and needs no password.
  checker := TPdf.Create;
  info := TJsonObject.Create;
  success := checker.PreLoadCheck('qa_output/memo_encrypted.pdf',info);
  if (success = False) then
    begin
      WriteLn(checker.LastErrorText);
      Exit;
    end;
  WriteLn('encrypted: ' + info.BoolOf('encrypted'));
  WriteLn('openPasswordRequired: ' + info.BoolOf('openPasswordRequired'));

  //  With the password, the PDF opens normally.
  reader := TPdf.Create;
  reader.UserPassword := 'user-secret';
  success := reader.LoadFile('qa_output/memo_encrypted.pdf');
  if (success = False) then
    begin
      WriteLn(reader.LastErrorText);
      Exit;
    end;
  WriteLn('pages: ' + reader.NumPages);

  //  Sample output:

  //  algorithm: aes-256
  //  PDF version: 1.7
  //  password needed to open: True
  //  encrypted: True
  //  openPasswordRequired: True
  //  pages: 2


  pdf.Free;
  json.Free;
  jsonOut.Free;
  checker.Free;
  info.Free;
  reader.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.