Assume that the $\phi$-hiding assumption is true, i.e. that for a composite number $m$, a PPT adversary A cannot distinguish between a prime $p_0$ that divides $\phi(m)$ and another prime $p_1$ that doesn't divide $\phi(m)$.
How to prove that a PPT adversary B cannot distinguish $q_0 = (r \cdot p_0) \bmod \phi(m)$ and $q_1 = (r \cdot p_1) \bmod \phi(m)$, where $r$ is a random integer between 1 and $\phi(m)$ inclusive?
I know the basic idea is to let A construct $q_0$ and $q_1$ and give them to B. But the issue is that A doesn't know $\phi(m)$.