Moore's Law is producing general purpose processors that can handle the necessary crypto functions in a negligible fraction of their capacity. Tiny special purpose chips can also be produced inexpensively for fulfilling the crypto demands of special applications. Thus we are about to be freed from the constraints of the past. These algorithms, crucial for digital signatures and key management, do not require the communicating parties to possess a shared key that only they have. Yet this new freedom is likely to make little difference in practice.
Strong cryptography is required for security.
However, strong cryptography alone does not guarantee security. Almost all security problems that keep surfacing with monotonous regularity are caused by economic and social factors, not defects in mathematical cryptography. There are no signs that this situation is about to change. The economic constraint comes from the desire for novelty over usability and security. Some of it can be blamed on the structure of the industry.