What is the principle behind the "Encryption at Rest" strategy?

The principle behind the "Encryption at Rest" strategy is centered on protecting data stored on devices by encrypting it to prevent unauthorized access. This form of encryption ensures that sensitive information, when not actively in use, remains safeguarded against potential data breaches or unauthorized retrieval.

Encryption at rest is critical because it secures data that is stored on hard drives, cloud services, or any other storage medium. By encrypting this data, even if an unauthorized individual gains access to the physical storage medium, they would not be able to decipher the information without the appropriate decryption keys. This strategy is particularly important for compliance with data protection regulations and for establishing trust with customers regarding data privacy.

The other options presented, while related to data security, do not align with the specific purpose of encryption at rest. For instance, encrypting data during transmission addresses the security of data in motion rather than data that is stored. Keeping backups of encrypted data pertains to data availability and recovery, rather than the primary focus of protecting stored data. Lastly, relying solely on encryption as the sole form of data protection neglects a more holistic approach to cybersecurity, which should incorporate multiple layers of security controls.