I created a modal input form that allows people to enter data, and upon submit creates a PDF document that gets stored in a document library. From there, it goes through a workflow based on people in various departments editing the document. When the document gets to the final stage, it is complete and gets stored in an "archive" document library. Once in here, I want the PDF to no longer be editable, and have the document and the library be read-only.
I was easily able to make the library "read-only" by assigning read access to every group other than admins, but when logging in as other users I can still edit the document.
I have read suggestions online about checking out all document to an admin account so users cannot edit the file or using an event receiver of some kind, but I really want to shy away from those approaches if possible. I am wondering if anyone has any clues as to how to make PDF documents in a document library read-only.