試験312-50v13-JPN トピック1 問題141 スレッド

The best choice is encrypting stored data with quantum-resistant algorithms because the scenario's core risk is long-term confidentiality of data at rest in a cloud environment under a future where large-scale quantum computing could break widely used public-key schemes. In CEH cryptography coverage, the most direct way to protect confidentiality is to use strong encryption that remains secure against the expected attacker capabilities. "Harvest now, decrypt later" is a practical concern: adversaries can copy encrypted data today and wait until new capabilities make decryption feasible. Therefore, the control must be cryptographic and future-resistant, not merely procedural or architectural.
Option B aligns with post-quantum readiness by moving encryption and key-establishment mechanisms toward quantum-resistant primitives. This is especially important for protecting stored records over long retention periods. Even if symmetric encryption such as AES is generally more resilient to quantum attacks than classical public-key algorithms, organizations still must ensure appropriate key sizes, robust key management, and quantum-resistant approaches where public-key cryptography is used for key exchange, key wrapping, or digital signatures that support storage encryption workflows.
Option A, distributing fragments, can improve availability and limit exposure in some breach scenarios, but it does not replace encryption and does not guarantee confidentiality if fragments are obtained. Option C is not applicable because the problem is stored cloud data, not quantum communications. Option D is a good governance practice, but it is not itself a cryptographic control that ensures confidentiality. The priority, per CEH-aligned cryptographic defense principles, is quantum-resistant encryption and key management for data at rest.