It's known that Grover's Algorithm quadratically reduces the difficulty of breaking AES and nearly all other symmetric encryption systems, as well as nearly all

It's known that Grover's Algorithm quadratically reduces the difficulty of breaking AES and nearly all other symmetric encryption systems, as well as nearly all hash functions. So it reduces AES 128 to O(sqrt(2^128)) = O(2^64) difficulty, (brute forceable) AES 192 to O(2^96) difficulty, (brute forceable by major state level actors) and AES 256 to O(2^128) difficulty. (secure) It's possible that they re-discovered Grover's Algorithm, in which case this is a big fat nothingburger. If/when quantum computers become widespread, we just switch from AES 128 by default to AES 256 by default, and talk about other things. On the other hand, it's possible that they invented a new quantum attack on AES, which does an exponential speedup, as in AES 128 can be broken in O(log(2^128)) = O(128) time, AES 256 can be broken in = O(256) time, etc. If that's the case we get to reinvent symmetric key cryptography, similar to what we're currently doing with nearly all public key encryption schemes. Shor's algorithm does an exponential speedup on many classes of discrete log problems, which breaks encryption schemes based on integer factorization, elliptic curves, discrete log etc. All standardized public encryption schemes are broken by Shor's algorithm. Note that when we say things like "AES is secure" that's shorthand for "AES is not known to be insecure". We don't have a proof that AES is secure, and if you did prove that AES is secure, that would probably imply P != NP which would be pretty neat. If someone proves P=NP, then all known encryption schemes except perhaps quantum encryption (which is unworkable at scale) is broken, and e-commerce as we know it is basically fucked.