35. Which of the following authentication methods provides non-repudiation? a. GMAC b. HMAC c. MAC d. MD5 e. SHA-2 f. Any hash built with the Merkle-Damgrd (M-D) construction. g. None of the above 36. Which of the following authentication methods requires exchanging a secret key between the sender and the recipient? a. GMAC b. HMAC c. MAC d. MD5 e. SHA-2 f. Any hash built with the Merkle-Damgrd (M-D) construction. g. It's hashing, not encryption, so no key is ever required