A Cryptography Engineer’s Perspective on Quantum Computing Timelines

If a quantum computer becomes stable enough to break RSA-2048, it means the hardest problem (fault-tolerant scaling) has been largely solved. From that point, the gap to attacking AES-128 is no longer about feasibility, but about efficiency. While AES-128 wouldn’t fall immediately, it would move from “theoretical concern” to “practical target,” because the remaining challenges are engineering optimizations rather than fundamental barriers.