Considering a CPA-secure version of RSA where the ciphertext is just a rundom element from $Z^*_N$. Does that meet the anonymity requirement in which an cpa adversary cannot distinguish between a message encrypted using Alice's public key and a message encrypted using Bob's public key?
My question is related to the experiment in which the adversary is given Alice's public key $pk_A$ and bob's public key $pk_B$ and choose a message $m$ from $Z^*_N$. Then the adversary given the ciphertext created by encryption using $pk_A$ or $pk_B$. The adversary task is to tell what public key has been used.