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Download and encrypt file to cache

Aug 12 '13 at 15:06

Hi. I have a requirement to develop an app for both iOS and Android. This app streams media and docs from a server, but it must also offer the optino to download documents and keep them encrypted on disk for offline usage. Think of it as a "DRM cache". Of course I understand this is not perfect, I just need a reasonable way to prevent users from getting the docs from cache and moving/viewing them on another app (the one we are developing expires if the subscription is not renewed, and will no longer decrypt the stored files). Looking at your options, I thought about combining the HTTP+Crypt module, so that the file is downloaded and encrypted on disk using a key generated locally only for this copy of the client, probably based on some hw info. Looking at your API this looks like something easy (maybe I need to generate a tmp file first to encrypt, but this is ok). Then comes what I think is the more complex part: can I decrypt this file on disk on-the-fly to memory, so it can be read/displayed, or do I need to decrypt it also to a tmp file (which would be more "dangerous", so to speak?) Thanks in advance for your help. Your documentation is so complete that it is easy to get lost in it. Take it as a compliment, of course!