Which statement best defines HMAC?

Which statement best defines HMAC?

• A. A mechanism that provides confidentiality by encrypting data with a symmetric key.
• B. A type of MAC that uses a cryptographic key along with a cryptographic hash function.
• C. A public-key encryption scheme.
• D. A random number generator.

Answer: (B)

HMAC is a type of MAC that uses a cryptographic key along with a cryptographic hash function. It produces a short authentication tag by combining a secret key with the message and hashing the result, so anyone with the same key can verify that the message has not been altered and that it came from the holder of the key. This provides integrity and authenticity, but not confidentiality—HMAC does not encrypt the data. It’s not a public-key encryption scheme, and it’s not a random number generator. The essence is a keyed hash-based code used to authenticate messages.

HMAC is a type of MAC that uses a cryptographic key along with a cryptographic hash function. It produces a short authentication tag by combining a secret key with the message and hashing the result, so anyone with the same key can verify that the message has not been altered and that it came from the holder of the key. This provides integrity and authenticity, but not confidentiality—HMAC does not encrypt the data. It’s not a public-key encryption scheme, and it’s not a random number generator. The essence is a keyed hash-based code used to authenticate messages.