What does Grover's algorithm mean for AES?
Much less than Shor's algorithm means for RSA: it weakens symmetric encryption and hashing, but does not break them. Lov Grover showed in 1996 that a quantum computer can search through possibilities in about the square root of the usual number of steps. Applied to guessing a key, that roughly halves the key length in bits: in theory, a 128-bit AES key behaves more like a 64-bit one. In practice the attack is one very long chain of steps that cannot be usefully split across many machines, so even AES-128 stays far from easy to break. The common advice is simple: use AES-256 for data that must stay secret for a long time, and SHA-256 or stronger for hashing. Most modern systems already support both, so this part of the change is usually a configuration choice, not a migration project. The real work lies with the public-key methods.