A client brought to my attention that a password protected and watermarked document I shared with him was stripped of all protection when he uploaded it via Google Drive. Would you please indicate what further measures I can take to allow the protections I have put into place with Adobe Acrobat Pro XI to remain intact? Thank you.
What do you mean by "protection": "open password" or "permissions password". If you secure a PDF with only "permissions password" intending to limit what the document's recipient can do, then, when you do that in Acrobat, you get an alert that all Adobe products respect restrictions set by permissions but the 3rd-party PDF Viewers may not respect them. This protection technology in Acrobat/Reader is very old, going back to the days when Reader was the only game in town. Now that there are many other PDF Viewers many of them do not conform to the published standards (ISO-32000-1). Google Drive's PDF Viewer is one of those.
The bottom line is that you cannot rely on the "permissions password" in Acrobat to enforce restrictions on what the recipients of your PDFs can do, unless all of them use Adobe Reader. There are even Web sites which will strip protection for you (but you'll have yo upload your PDF to them, which means that they may use its content). If you really want to restrict what the users can do with your documents, you need to use one of many available DRM solutions, but that could be expensive.