Question 17 (5 points)

Concisely explain how using chaining/feedback or nonce-based IV/counter makes a stronger cryptosystem than the ones that do not use such a mechanism.

Question 15 (5 points)

In this question, you will encrypt a message using RSA for given parameters below.

p = 5, q = 11, e = 3, M = 9

Derive the private key.

Question 16 (10 points)

In the question above, show the process of decrypting the ciphertext and its result. You need to derive the ciphertext first and then show the decryption process.

Question 14 (15 points)

Alice and Bob use the Diffie-Hellman key exchange technique with a common prime p = 71 and a primitive root a = 7

a. If Alice A has private key XA = 5, what is Alices public key YA?

b. If Bob has private key XB = 12, what is Bs public key YB?

c. What is the shared secret key?

Question 13 (10 points)

Describe concisely the advantages and disadvantages of symmetric-key cryptography compared to those of public-key cryptography.