What does data encryption at rest protect?

• A. Data during transmission over networks
• B. Data stored on devices when not actively in use
• C. Data in use in application memory
• D. Data temporarily saved in cookies

Answer: (B)

Data encryption at rest specifically addresses the security of data that is stored on devices when it is not actively accessed or processed. This means that any sensitive information, files, or databases stored on hard drives, cloud storage, or other storage mediums is protected from unauthorized access, even if the device is compromised or accessed by physical means.

Encrypting data at rest ensures that it is unreadable without the appropriate decryption keys, thus safeguarding it against theft or exposure in case of a breach. This is particularly crucial for protecting confidential information, such as personal data, financial records, and proprietary business information, which could be exploited if accessed unencrypted.

On the contrary, other options describe scenarios that data encryption at rest does not cover. For instance, data during transmission requires encryption methods like SSL/TLS, and data in use refers to information actively being processed by applications that is often secured with different techniques like memory protection or application-level encryption. Temporary data saved in cookies is usually managed by the browser and not directly linked to encryption at rest. Thus, the focus of encryption at rest is centered around safeguarding data that is stored and not being actively utilized.