Which of the following is MOST appropriate for protecting confidentially of data stored on a hard drive?

Protecting the confidentiality of data stored on a hard drive (data at rest) requires encryption. The Advanced Encryption Standard (AES) is the current U.S. federal government standard and the globally accepted industry standard for symmetric block encryption. It is strong, efficient, and widely implemented in full-disk and file-level encryption solutions. While 3DES is also an encryption algorithm, it is an older, slower standard with a smaller block size, making it less secure and less appropriate than AES for modern applications. MD5 and SHA-2 are hashing algorithms designed to provide data integrity, not confidentiality, as they are one-way functions and cannot be reversed to recover the original data.

1. National Institute of Standards and Technology (NIST). (2001). FIPS PUB 197: Advanced Encryption Standard (AES). "This standard specifies the Rijndael algorithm

a symmetric block cipher that can process data blocks of 128 bits

using cipher keys with lengths of 128

192

and 256 bits. AES is a specification for the encryption of electronic data..." (Page 1

Section 1).

2. National Institute of Standards and Technology (NIST). (2020). Special Publication 800-57 Part 1 Rev. 5: Recommendation for Key Management. Table 2

"Cryptographic algorithms and their main purpose

" explicitly lists AES for providing confidentiality and SHA-2 for digital signatures

HMAC

and hash-based key derivation

but not confidentiality. The document also notes 3DES is deprecated. (Page 54

Section 5.6.1).

3. National Institute of Standards and Technology (NIST). (2007). Special Publication 800-111: Guide to Storage Encryption Technologies for End User Devices. "Full disk encryption can be implemented using a variety of encryption algorithms

such as the Advanced Encryption Standard (AES) and the Triple Data Encryption Algorithm (TDEA) [also known as Triple DES]." This document establishes the use of these algorithms for disk encryption

with AES being the modern standard. (Page 8

Section 3.1).

4. Saltzer

J. H.

& Kaashoek

M. F. (2009). Principles of Computer System Design: An Introduction. MIT OpenCourseWare. Chapter 6

"Security and Protection

" discusses the fundamental difference between encryption for confidentiality (e.g.

AES) and one-way hash functions for integrity (e.g.

SHA). (Section 6.4.2

Cryptographic Hashes; Section 6.4.3

Symmetric Key Cryptography).