I am trying to construct a proof that a scheme is not CPA-secure. In IND-CPA experiment, can the adversary generate a key(that may not be real secret key) and compute Enc(key, message)? Does the adversary knows the encryption scheme in IND-CPA experiment?
I need this as I want to prove that if a scheme B1 is not CPA-secure, a scheme B2 is not CPA-secure by the following logic: There exists an adversary A that can win IND-CPA experiment for scheme B1. Then I construct an adversary A' with the help of A to win IND-CPA experiment for scheme B2. But A' has to be able to compute Enc(key, message) for some key. I am unsure whether I can do so.