I notice that in many research papers (viz. "Universal hash proofs and a paradigm for adaptive chosen ciphertext secure public-key encryption" by Cramer and Shoup) the authors showed that their cryptosystem is IND-CCA secure under standard model. What does it mean? What does an adversary have access to in a challenger-adversary game?
Actually, my aim is to get a clear idea on IND-CCA secure under standard model. I am confused on the statemant like "The given public key cryptosystem is IND-CCA secure under Diffie-Hellman assumption ". Is this statemant means that this particuler cryptosystem is IND-CCA secure under standard model?