XOR或其他简单的文件混淆方法ios objective c。

I am working on an ios application that uses copyrighted pdf files. I am looking for some simple ways to obfuscate the files for security that won't require me to go through the additional Mass Market CCATS encryption review process but will also ensure the copyright holders I've done my bit to keep their data safa. I password protect the files of course, but I want to bring it a step or two further. Is there a simple method to XOR or otherwise hash or obfuscate a pdf file I'll be hosting on my server, then have the ios device download it and restore it to a regular password protected pdf file using objective-c code so it can save it in the documents directory (I'm not worried about its security on the device as much as when it's sitting on the server). I assume that this would be the same for any filetype.I am working on an ios application that uses co