I would like to know how Android, Windows, Linux, and OS X deal with DRM (Digital Rights Management) e-pub, pdf, and mp3 files. Basically, if I download a DRM file to my device (perhaps one that has an expiry date or forbids copying of the file), can't anyone write a custom (despite illegal in most countries, or perhaps even one for personal use written by a coder who knows enough about DRM) program to ignore the DRM portions of the file and turn it into a regular non-DRM file?
closed as too broad by Deer Hunter, RoraΖ, BadSkillz, TildalWave, John Deters Feb 5 '16 at 20:00
Please edit the question to limit it to a specific problem with enough detail to identify an adequate answer. Avoid asking multiple distinct questions at once. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.
As long as any program capable of reading the DRM protected file is working on your computer, experts can analyze it and write a program that circumvents DRM for that file for an indefinite amount of time.
There are DRM systems in which the key to decrypt the content is calculated just-in-time by a server. If you didn't save the key before expiration, you likely can't access this file with any software after expiration.