Delphi DLL 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. Delphi DLL

var
success: Boolean;
pdf: HCkPdf;
json: HCkJsonObject;
jsonOut: HCkJsonObject;
checker: HCkPdf;
info: HCkJsonObject;
reader: HCkPdf;

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 := CkPdf_Create();
success := CkPdf_LoadFile(pdf,'qa_data/pdf/two_page_memo.pdf');
if (success = False) then
  begin
    Memo1.Lines.Add(CkPdf__lastErrorText(pdf));
    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.
CkPdf_putUserPassword(pdf,'user-secret');
CkPdf_putOwnerPassword(pdf,'owner-secret');

//  An empty JSON asks for the defaults: AES-256, everything encrypted, every permission granted.
json := CkJsonObject_Create();
jsonOut := CkJsonObject_Create();
success := CkPdf_Protection(pdf,'encrypt',json,jsonOut);
if (success = False) then
  begin
    Memo1.Lines.Add(CkPdf__lastErrorText(pdf));
    Exit;
  end;

//  Nothing has been encrypted yet.  "pending" describes the security the PDF will be saved with.
Memo1.Lines.Add('algorithm: ' + CkJsonObject__stringOf(jsonOut,'pending.algorithm'));
Memo1.Lines.Add('PDF version: ' + CkJsonObject__stringOf(jsonOut,'pending.pdfVersion'));
Memo1.Lines.Add('password needed to open: ' + IntToStr(Ord(CkJsonObject_BoolOf(jsonOut,'pending.userPasswordRequired'))));

//  Writing the file applies it.
success := CkPdf_WriteFile(pdf,'qa_output/memo_encrypted.pdf');
if (success = False) then
  begin
    Memo1.Lines.Add(CkPdf__lastErrorText(pdf));
    Exit;
  end;

//  PreLoadCheck reports a file's encryption without loading it, and needs no password.
checker := CkPdf_Create();
info := CkJsonObject_Create();
success := CkPdf_PreLoadCheck(checker,'qa_output/memo_encrypted.pdf',info);
if (success = False) then
  begin
    Memo1.Lines.Add(CkPdf__lastErrorText(checker));
    Exit;
  end;
Memo1.Lines.Add('encrypted: ' + IntToStr(Ord(CkJsonObject_BoolOf(info,'encrypted'))));
Memo1.Lines.Add('openPasswordRequired: ' + IntToStr(Ord(CkJsonObject_BoolOf(info,'openPasswordRequired'))));

//  With the password, the PDF opens normally.
reader := CkPdf_Create();
CkPdf_putUserPassword(reader,'user-secret');
success := CkPdf_LoadFile(reader,'qa_output/memo_encrypted.pdf');
if (success = False) then
  begin
    Memo1.Lines.Add(CkPdf__lastErrorText(reader));
    Exit;
  end;
Memo1.Lines.Add('pages: ' + IntToStr(CkPdf_getNumPages(reader)));

//  Sample output:

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

CkPdf_Dispose(pdf);
CkJsonObject_Dispose(json);
CkJsonObject_Dispose(jsonOut);
CkPdf_Dispose(checker);
CkJsonObject_Dispose(info);
CkPdf_Dispose(reader);