Question

A security architect is preparing a cryptographic inventory ahead of the organization's post-quantum migration. Leadership asks which currently deployed algorithms require the least urgent action because they remain adequately secure against quantum attacks with modest parameter adjustments, versus those that are fundamentally broken by a cryptographically relevant quantum computer. Which recommendation is technically correct?

Accepted Answer

AES-128 should be upgraded to AES-256 to preserve security margin, while RSA and ECC must be replaced entirely with quantum-resistant algorithms because they are fundamentally broken by Shor's algorithm.

Answer

RSA-2048 and AES-128 are equally vulnerable to Shor's algorithm and both must be replaced with lattice-based schemes immediately.

Answer

AES-256 must be replaced because Grover's algorithm fully breaks all symmetric ciphers, while RSA can simply be extended to 4096-bit keys for quantum resistance.

Answer

SHA-256 and RSA are quantum-safe as-is, while AES requires migration to a post-quantum symmetric standard published by NIST.