FIPS 198-1 defines which of the following?

• A. The keyed-hash message authentication code (HMAC)
• B. Digital signatures
• C. AES
• D. RSA

Answer: (A)

HMAC is the mechanism defined by this standard. A keyed-hash message authentication code uses a cryptographic hash function together with a secret key to produce a fixed-size tag that accompanies a message. The tag lets the recipient verify both the message’s integrity and the sender’s identity (authenticity) because only someone with the shared secret key could generate the correct tag for a given message. FIPS 198-1 lays out how to construct HMAC, how to handle keys of different lengths, and the security considerations for using it with various hash functions (like SHA-256).

This standard is not about digital signatures, which rely on public-key cryptography to provide non-repudiation, nor about encryption algorithms like AES or RSA, which focus on confidential transformation of data. HMAC serves integrity and authenticity checks, not encryption or non-repudiation.