What does "data encryption at rest" involve?

Data encryption at rest specifically focuses on protecting data that is stored on physical media such as disk drives, databases, or storage systems. This type of encryption ensures that sensitive information is rendered unreadable when it is not actively in use, thereby safeguarding it from unauthorized access or breaches when the data is stored.

When data is encrypted at rest, even if an attacker gains access to the storage medium, they will not be able to decipher the data without the corresponding decryption keys. This is essential for complying with security standards and regulations that mandate the protection of personal and sensitive information.

The other options do not accurately represent data encryption at rest. Encrypting data that is actively being used pertains more to data in transit or during processing rather than when it is being stored. Similarly, focusing solely on backup data does not encompass the entirety of data encryption at rest, which includes all stored data, whether it's operational or backup. Encrypting only data transmitted over the network describes data in transit, which is a different aspect of data security.