The main reason to purchase a Blackberry, it's built-in encryption of messages, turns out to an hoax, the Canada government being in knowledge of the relevant encryption key since at least 2010 according to news.
Suffice to say this should hint the direction where things should go. What should be changing over time is the encryption algorithm, because it's the weak link. If your algorithm never changes over time, how can you expect it not be cracked ?
Ideally, the encryption key should be a dynamically generated algorithm based on so many parameters that it makes it not uncrackable, but substantially expensive for even the most sophisticated surveillance.