> I'm not sure if quantum computing helps here in any way Theoretically a quantum computer can brute-force AES-256 using 2^128 sequential steps using Grover's

> I'm not sure if quantum computing helps here in any way Theoretically a quantum computer can brute-force AES-256 using 2^128 sequential steps using Grover's algorithm (i.e. a quadratic advantage over a classical computer). Parallelization diminishes the advantage, e.g. if you're limited to 2^64 sequential steps, you get a 2^64 speedup over classical, for a cost of 2^192 which is still ridiculously large. Thus quantum computing is not a relevant threat for AES-256 or most other 256-bit symmetric crypto.