how does decryption differ from reversing a hash algorithm?

Question

I am struggling to understand how one is fast enough to underly the entire internet and how the other is so slow as to be functionally impossible.

As an expansion, since the public key is known, how then is the encrypted message irreversible?

In: 4

Answer 1

Encryption and decryption are information preserving operations.

Hash functions are not. If you hash a number into 64 bins, there are only 64 possible answers even through there are zillions of possible inputs. Clearly, this is not reversible.

The whole point of the hash is to be much smaller than the number of bits needed to store a copy of the information, while providing some evidence of tampering.