Suppose it is necessary to build a safe PRG. You have one PRP with $\epsilon = \frac{1}{2} ^ {45}$, and one PRF with $\epsilon = \frac{1}{2} ^ {55}$. There is no mathematical relationship in the PRP to PRF.
Can a safe PRG be built with them?
Does anyone have an explanation for this?
Because as far as i know when you have a repetition of $\epsilon = \frac{1}{2} ^ {80}$ then it is considered as the standard of a good encryption unless it is below but is there any trick here about this question?
