# Lecture 7: Cryptographic Hashes and Message Authentication Codes (MACs)

## Cryptographic Hash Functions

(True/False) Given a cryptographic hash function and some x, it is hard to find x' such that H(x) = H(x')

## Hash Function Applications

(True/False) The application presented relies on the one-way property of a cryptographic hash function

## Integrity and Authentication

(True/False) Encryption only gives you confidentiality but not integrity or authentication.

## Message Authentication Codes (MACs)

(True/False) MACs ensure confidentiality and integrity

## AES-EMAC

(True/False) AES-EMAC is a secure MAC even if the k1 and k2 are identical

## Authenticated Encryption

(True/False) If the MAC is over the plaintext message instead of the encrypted message, the described scheme still provides confidentiality, integrity, and authentication.

## Is AES-EMAC a hash function?

(True/False) AES-EMAC is a hash function if the key is kept private

## HMAC

(True/False) The underlying hash function must be collision resistant for the security of HMAC to hold