CEC 304 Data Security and Integrity Resit 2023

About this paper

CEC 304: University of Buea, College of Technology, Resit Examination, July 2023, Instructor Sone Ekonde, Answer ANY TWO of three questions: Question 1, elliptic-curve cryptography (ECC encryption and ECDH key exchange over a small curve mod 11, using a table of precomputed point multiples); Question 2, briefly explaining MD5 (hash length, padding, block size), implementing a toy XOR-based hashing algorithm on hexadecimal sub-blocks, breaking a substitution cipher given the first plaintext letter, and hand-computing two Feistel rounds of a scaled-down DES cipher with given permutation and S-box tables; Question 3, explaining how a Trusted Third Party reduces the number of symmetric keys needed (with CBC mode and node-identifier concatenation for the IV), and a full RSA worked example (key generation, encryption, decryption, and how to defend against public-key substitution/man-in-the-middle attacks).