Question: Explain the operation of a stream cipher and its key differences with block

ciphers. Describe how stream ciphers can be vulnerable to attacks and propose a

method to improve their security.

Question: Discuss the structure of the AES algorithm. How does it achieve security

through its different rounds? Illustrate the role of each operation in one round.

Question: Describe how a public key scheme works and give an example with RSA.

What are the main advantages and limitations of using RSA?

Question: Explain the role of cryptographic hash functions in security systems and

discuss the properties that make a hash function suitable for cryptographic

applications.

Question: Define a MAC and explain how it differs from digital signatures. What

scenarios are most appropriate for the use of MACs?

Question: Discuss the process of creating and verifying digital signatures. Why are

digital signatures considered a fundamental tool in modern digital communications?