Hi,
Here is a summary of the "owner password" behavior:
1. An "owner password" on a PDF file is like a "no smoking" sign with no enforcement;
2. When a PDF editor sees this password, it has the option to ignore it or honor it. That's why NitroPDF sees this password but still readily allow you to reset the permissions;
3. EO.Pdf can do the same. You can use the following code to reset a PDF file protected by owner's password (no matter the file is encrypted by EO.Pdf or by another editor):
Code: C#
//Open a PDF file encrypted with owner password. Note that
//there is no need to provide the owner password at all. The
//file will open file without the password
PdfDocument doc = new PdfDocument(encrypted_pdf_file_name);
//Reset the permission
doc.Security.Permissions = PdfDocumentPermissions.All;
//Save it to a new file. The new file now has no permission restrictions
doc.Save(new_unencrypted_pdf_file_name);
There is nothing proprietary or non-standard about this. On the contrary, because the PDF file format standard is open and it puts no technical barrier for reading an owner password protected PDF file, everyone can read such a file without needing the password at all. The only part that is "non-standard" in the above code is that, if you were writing a PDF editor with our library, you "suppose" to add some code to ask for the user for password before your code proceed to reset the permissions. However as you have already discovered, nobody (except for Adobe) seriously enforces this rule;
4. By the same token, when you set the restrictions with Editor X, Editor Y can choose not to "honor" it at all.
The only case where the owner password really matter is, if a file is encrypted with both owner password and user password, then at least one of these two password is needed in order to open the file. In this case owner password can be used to correctly decode (open) the file.
Hope this clears up. Please feel free to let us know if you still have any questions.
Thanks!