What is the difference between a non-secure random number generator and a secure random number generator?

Question

As the title says: What is the difference between a non-secure random number generator and a secure random number generator?

Answer 1

No computationally feasible algorithm should:

• recover the seed, or
• predict the "next bit"

for a secure random number generator.

Example: a linear feedback shift register produces lots of random numbers out there, but given enough output, the seed can be discovered and all subsequent numbers predicted.