Which statement describes data encryption at rest versus in transit?

• A. At rest protects stored data; in transit protects data moving over networks (TLS/HTTPS).
• B. In transit protects stored data; at rest protects data moving over networks (TLS/HTTPS).
• C. At rest protects data during processing; in transit protects data during backups.
• D. At rest uses TLS; in transit uses AES 256.

Answer: (A)

Encryption protects data based on its state: at rest means data stored on disks, in databases, or backups; in transit means data moving across networks. The statement that encryption at rest protects stored data is correct because it ensures that files, databases, and backups remain unreadable without the proper key if storage is accessed directly. The statement that encryption in transit protects data moving over networks using TLS or HTTPS is correct because these protocols secure the channel between sender and receiver, preventing eavesdropping and tampering during transmission.

The other options mix up these roles or describe scenarios that aren’t about protecting data in transit or at rest (such as protection during processing or backups). They also pair TLS with at-rest or misstate the typical use of AES-256, which is commonly used for at-rest encryption rather than being the exclusive mechanism for in-transit protection.