This article debunks the idea that quantum computers halve the security of symmetric keys via Grover’s algorithm, showing that the required depth and parallelization make an AES-128 key search infeasible. Concrete gate-count estimates and NIST’s MAXDEPTH guidelines confirm that AES-128 (and larger keys) remain secure against practical quantum attacks.

• Grover's algorithm can't be parallelized without losing its quadratic speedup, so splitting the key search across many quantum processors just increases total work rather than reducing time needed.
• Cracking AES-128 in 10 years would require ~1.4×10^14 parallel circuits of 724 qubits each with a circuit depth around 2^64 — far beyond any feasible quantum hardware.
• Breaking 256-bit ECC via Shor's algorithm would be about 4.3×10^23 times faster than breaking AES-128 via Grover's, showing symmetric keys aren't the weak link.
• NIST's post-quantum standards (Category 13, MAXDEPTH limits, IR 8547 roadmap) keep all AES key sizes approved without requiring a move to 256-bit symmetric keys.