I agree the phone in authenticator is open to hijacking through means of proxy. It seems the only advantage of this over the keychain/iphone authenticator is ease of use though. It would be nice if they could make it so that a single authenticator code worked across all accounts on the one battlenet account if used within a minute of each other or some such. It is really only having to wait for 5 unique numbers to come up which slows down log ing with these authenticators.