# Lecture 8: Public Key Encryption, Hashing

- Notes
- Sp20 Slides
- Playlist (length: 1:07:18)

## El Gamal Padding

(True/False) The padding scheme presented only works if the message size is less than or equal to the number of plaintext bits

## Hybrid Encryption

(True/False) Hybrid encryption works by using symmetric encryption to encrypt a message, and encrypting the symmetric key with asymmetric encryption.

## El Gamal Security + Asynchronous Encryption

(True/False) El Gamal is secure if the Discrete Log problem holds

## El Gamal Intuition

Which two cryptographic techniques/protocols is El Gamal built on?

## 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.