Week 7: Public-Key Cryptography

Question 1

How do Merkle Puzzles work?

Answer 1

1. Alice generate n puzzles, when one is solved it reveals an ID d and key k
2. Alice sends puzzle set to Bob, he picks random puzzle i and solves it to get ki and di
3. Bob then sends di to Alice and they both know to use key ki

Question 2

What are some applications of assymetric-key cryptography?

Answer 2

• Key agreement/exchange (ie. DHE, ECDHE)

- Digital signatures (ie. RSA, DSA)

Question 3

How does Diffie-Hellman work?

Answer 3

Given common generator g,
Alice generates key a and sends g^a to Bob.
Bob generate key b and sends g^b to Alice.
Now both can generate g^ab

Question 4

What is the weakness of Diffie-Hellman?

Answer 4

Susceptible to Man in Middle attacks.