AES-128 is safe against quantum computers. SHA-256 is safe against quantum computers. No symmetric key sizes have to change as part of the post-quantum transition. This is a near-consensus opinion amongst experts and standardization bodies and it needs to propagate to the rest of the IT community. The rest of this article backs up this claim both technically and with references to relevant authorities.
Original article: https://words.filippo.io/128-bits/
TL;DR: https://hackaday.com/2026/04/25/quantum-computers-are-not-a-threat-to-128-bit-symmetric-keys/
It’s secure because it’s symmetric. It can’t be cracked because there is no exposed secondary information.
Asymmetrical encryption relies on using information which is visible to the outside world to compute two keys using math that is very difficult to reverse. Quantum computers make that math MUCH easier.
But since symmetric encryption doesn’t do that. It’s safe.