# Lecture 7: Public Key Exchange

- Sp20 Slides
- Playlist (length: 59:11)

## Asymmetric Encryption

(True/False) Asymmetric encryption is the same as symmetric, except a user has two private keys instead of one

## One-Way Functions

Is the one-time pad (with an unknown-key) a one-way function?

## Discrete Logarithm

(True/False) Given g^x (mod p) and p, it is difficult to find x even when given additional knowledge of g

## Diffie-Hellman Key Exchange

Why can't Alice and Bob simply send their keys a/b to eachother in order to compute the shared g^(ab)?

## Diffie-Hellman Key Exchange Security

When Malice performs the MiTM attack, she must pick the same g^m (mod p) that she sends to both parties

## Detecting Pairing MiTM attacks

Why don't we always use this method of entering a digest of the derived key to check that the same key was derived?

## Public Key Encryption and Semantic Security

What is the main difference between the IND-CPA and Semantic Security games we've seen in class?

## El-Gamal Encryption Scheme

(True/False) In El-Gamal encryption, the exponent r must be random