Are real-or-random(rr) model and LR-model are equivalent?
In the definition of ciphertext indistinguishability, LR-model is used. However I think rr model and LR model are somewhat equivalent.
Here is what I really want to know:
When proving some cryptosystem(ex. ElGamal under DDH) are IND-CPA secure, can we just use real-or-random model? If not, how can we prove that ElGamal is IND-CPA secure using LR model?