Delphi DLL 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. Delphi DLL

var
success: Boolean;
pdf: HCkPdf;
info: HCkJsonObject;

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 := CkPdf_Create();
info := CkJsonObject_Create();

//  A PDF that is not encrypted.  Nothing but "encrypted" is reported for it.
success := CkPdf_PreLoadCheck(pdf,'qa_data/pdf/two_page_memo.pdf',info);
if (success = False) then
  begin
    Memo1.Lines.Add(CkPdf__lastErrorText(pdf));
    Exit;
  end;
Memo1.Lines.Add('two_page_memo.pdf');
Memo1.Lines.Add('  encrypted: ' + IntToStr(Ord(CkJsonObject_BoolOf(info,'encrypted'))));

//  A PDF that needs a password to open.
success := CkPdf_PreLoadCheck(pdf,'qa_data/pdf/encrypted_user_password.pdf',info);
if (success = False) then
  begin
    Memo1.Lines.Add(CkPdf__lastErrorText(pdf));
    Exit;
  end;
Memo1.Lines.Add('encrypted_user_password.pdf');
Memo1.Lines.Add('  encrypted: ' + IntToStr(Ord(CkJsonObject_BoolOf(info,'encrypted'))));
Memo1.Lines.Add('  method: ' + CkJsonObject__stringOf(info,'method'));
Memo1.Lines.Add('  algorithm: ' + CkJsonObject__stringOf(info,'algorithm'));
Memo1.Lines.Add('  openPasswordRequired: ' + IntToStr(Ord(CkJsonObject_BoolOf(info,'openPasswordRequired'))));

//  A PDF that opens without a password but is restricted.  The permissions are readable without
//  any password.
success := CkPdf_PreLoadCheck(pdf,'qa_data/pdf/no_copy_permission.pdf',info);
if (success = False) then
  begin
    Memo1.Lines.Add(CkPdf__lastErrorText(pdf));
    Exit;
  end;
Memo1.Lines.Add('no_copy_permission.pdf');
Memo1.Lines.Add('  encrypted: ' + IntToStr(Ord(CkJsonObject_BoolOf(info,'encrypted'))));
Memo1.Lines.Add('  openPasswordRequired: ' + IntToStr(Ord(CkJsonObject_BoolOf(info,'openPasswordRequired'))));
Memo1.Lines.Add('  may copy: ' + IntToStr(Ord(CkJsonObject_BoolOf(info,'permissions.copy'))));

//  The typical use: ask for a password only when one is needed, then load.
success := CkPdf_PreLoadCheck(pdf,'qa_data/pdf/encrypted_user_password.pdf',info);
if (success = False) then
  begin
    Memo1.Lines.Add(CkPdf__lastErrorText(pdf));
    Exit;
  end;
if (CkJsonObject_BoolOf(info,'openPasswordRequired') = True) then
  begin
    //  An application would prompt for the password here.
    CkPdf_putUserPassword(pdf,'secret');
  end;
success := CkPdf_LoadFile(pdf,'qa_data/pdf/encrypted_user_password.pdf');
if (success = False) then
  begin
    Memo1.Lines.Add(CkPdf__lastErrorText(pdf));
    Exit;
  end;
Memo1.Lines.Add('loaded, pages: ' + IntToStr(CkPdf_getNumPages(pdf)));

//  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

CkPdf_Dispose(pdf);
CkJsonObject_Dispose(info);