What does HMAC stand for?

• A. Hash-based Message Authentication Code
• B. Hashed Message Authentication Code
• C. High-level Message Authentication Code
• D. Hash-based Message Access Code

Answer: (A)

HMAC stands for Hash-based Message Authentication Code. It’s a specific construction that uses a cryptographic hash function together with a secret key to create a short tag that accompanies a message. The recipient, who also knows the secret key, can recompute the tag and verify it matches; if it does, the message is authentic and hasn’t been altered. This combination provides both integrity and authenticity, since only someone with the secret key could generate the correct tag. The HMAC design also uses an inner and outer hashing process to protect against certain weaknesses that simple keyed hashes can have, making it robust for real-world use with hash functions like SHA-256. The other options aren’t the standard name or do not describe the method correctly.