Which of the following cryptographic solutions protects data at rest?

Full Disk Encryption (FDE) is a cryptographic solution specifically designed to protect

data at rest. It works by encrypting the entire contents of a storage drive, including the

operating system, application files, and user data. This ensures that if the physical

storage device is lost or stolen, the data remains unreadable to unauthorized individuals

who do not possess the decryption key. FDE provides a comprehensive layer of

confidentiality for all data stored on the encrypted medium.

A. Digital signatures: These primarily provide data integrity, authenticity, and non-

repudiation. They verify that data has not been altered and originates from the

claimed sender, but they do not encrypt the entire dataset to protect its confidentiality

at rest.

C. Private key: A private key is a component of asymmetric cryptographic systems

used for decryption or creating digital signatures. While essential for accessing

encrypted data (which might be at rest), the key itself is not the overall "solution" that

protects the bulk of data at rest; rather, it's a tool used within such solutions. Full Disk

Encryption is a more precise and complete solution.

D. Steganography: This technique focuses on concealing the existence of data within

other data, aiming for obscurity rather than providing cryptographic protection

(confidentiality through encryption) for data at rest.

Full Disk Encryption & Data at Rest:

National Institute of Standards and Technology (NIST). (2018). NIST Special Publication

800-111: Guide to Storage Encryption Technologies for End User Devices. Section 2.1

"Data-at-Rest", Section 3.1 "Full Disk Encryption".

URL: https://csrc.nist.gov/publications/detail/sp/800-111/final

Specific: Section 2.1 defines Data-at-Rest (DAR) and mentions encryption as a

protection strategy. Section 3.1 defines FDE as encrypting the entire hard drive.

Digital Signatures:

National Institute of Standards and Technology (NIST). (2001). NIST Special Publication

800-32: Introduction to Public Key Technology and the Federal PKI Infrastructure.

Section 2.1.3 "Digital Signature".

URL: https://csrc.nist.gov/publications/detail/sp/800-32/archive/2001-11-26

Specific: Section 2.1.3 describes the purpose of digital signatures as providing data

integrity and non-repudiation.

Private Key:

National Institute of Standards and Technology (NIST). (2020). NIST Special

Publication 800-57 Part 1 Revision 5: Recommendation for Key Management: Part 1 –

General. Section 5.1 "Overview of Asymmetric Cryptographic Key Pairs".

URL: https://csrc.nist.gov/publications/detail/sp/800-57-part-1/rev-5/final

Specific: Section 5.1 describes private keys as secret components of key pairs in

asymmetric cryptography.

Steganography:

National Institute of Standards and Technology (NIST). (2021). NIST Internal Report

(NISTIR) 7298 Revision 3: Glossary of Key Information Security Terms. Page 177.

URL: https://csrc.nist.gov/publications/detail/nistir/7298/rev-3/final

Specific: Page 177 defines steganography as "The art or science of concealing a

message, file, or information within another message, file, or information."