What does "encryption at rest" signify?

"Encryption at rest" specifically refers to the practice of securing data that is stored on physical media, such as hard drives or solid-state drives, by using encryption techniques. This form of encryption ensures that data is not accessible to unauthorized users while it is idle or inactive and is a critical component of data protection strategies, particularly for sensitive or confidential information.

This type of encryption helps protect data from breaches that might occur if someone gains physical access to storage devices. By encrypting the data itself, even if an attacker were to steal the physical storage medium, they would still be unable to read the contents without the appropriate decryption key.

The other options do not align with the concept of "encryption at rest." Protecting data temporarily in use refers to different mechanisms, often related to data in transit or actively processed data. Protecting data during transmission over a network involves encryption in transit, which is aimed at securing data as it moves between systems. Meanwhile, the notion of permanently destroying data is not applicable to encryption, as it pertains to data eradication rather than securing it. Thus, the focus of encryption at rest is unequivocally on data that is stored and not actively being used or transmitted.