No, we probably wouldn't. These one-way functions have some nice properties that we use in RSA and Diffie-hellman, like commutativity and the fact that encrypti

No, we probably wouldn't. These one-way functions have some nice properties that we use in RSA and Diffie-hellman, like commutativity and the fact that encryption is a permutation, but these properties come with caveats in that they are considerably easier to break. A simple consequence is that we need something like 1024 bits for a strong RSA key, but SHA-256 is still miles out of reach of being attackable.