Our PDF Stamper creates a new PDF for each buyer with security settings that may differ from the original PDF file you upload, but in a predictable way.
Because of the way our Stamper works as a PDF authoring program itself and creates a brand-new PDF document for each buyer, it has to apply any security settings to each Stamped copy itself; these cannot be simply duplicated or "carried over" from the original source document. Thus, the Stamper applies sensibly secure document permissions that forbid actions relevant to piracy/plagiarism or removal of the stamp, while allowing other actions that many PDF sellers may actually want buyers to be able to perform, and giving you the option to allow or forbid printing or copy/pasting of text.
Our PDF Stamper adds the longest possible, randomized Master password to each buyer's Stamped copy; this encrypts the file's contents and locks the document permissions it applies to the file, which would forbid editing capabilities relevant to piracy or plagiarism: namely, actions pertaining to document creation (adding/deleting/changing the existing content) and document assembly (adding/removing/reordering pages). You can also forbid printing and copy/paste actions for stamped files by using the &pdf_allow_copy=n&pdf_allow_print=n parameters in our PDF stamping URL.
However, the Stamper also permits superficial editing actions which do not affect the original content, such as filling in form fields, adding comments, and the ability to "sign" the document digitally. For instance, a buyer might be expected to type some data into some form fields provided in the file, add a digital signature key to prove it was really them who filled in the form, and then submit the completed file somewhere.
