Question 1: Briefly compare and contrast how asymmetric cryptography is used to provide encryption as opposed to how it can be used to provide a digital signature.
Question 2: What is the purpose of the Diffie-Hellman algorithm? What are its major strength(s) and weakness(es)?
Question 3: Using RSA, let p = 17, q = 13 and e = 5. What are the complete public and private keys?
Question 4: Briefly explain how steganography is implemented in order to hide a textual message within a photographic image
Question 5: A foreign navy has implemented a secure communications system in which submarine commanders transmit a single 5-letter message every day. The messages may only use capital (English) letters, and all messages are equally probable. A crypto device encrypts each message into 20 bits of ciphertext.
- What is the entropy of the plaintext message?
- What is the entropy of the ciphertext message?
- Is this a good cryptosystem? Why or why not?