An encryption algorithm is never going to be 100% secure. As sophisticated as encryption security is becoming, cyber attacks are also evolving at a rapid pace.
And the theory is that, if a man made it (with the help of a powerful machine), then another man (with an equally powerful machine and enough time and resources) will eventually be able to break it.
The key there is time.
The future of encryption algorithms seem to be focused on extending the time it would take to hack into a system, by creating so many possibilities, that the key is effectively buried by the amount of time it would take to find.
For example, a method called Honey Encryption will deter hackers by creating lots and lots of fake data every time someone tries to enter an incorrect key code.
Another method which sounds pretty awesome (but which, I have to admit I don't fully understand) is "quantum key distribution", which involves keys embedded in photons over fiber optic.