How does encryption work? For example how could i assure that files sent electronically cannot be read by anybody else other than the recipient.
Correct - everything in the world is made to be broken. Don't believe me? Ask a computer techie - they won't fix anything to the point where it's impossible to be broken, otherwise they'd be out of a job. Same with encryption and security analysts. However, it is, with great difficult, possible to crack all forms of encryption. Really depends what it is that you're sending and who you don't want it read by.