Exam Questions on Cryptography for Software Development and Computer Networking Students, Exams of Cryptography and System Security

Download Exam Questions on Cryptography for Software Development and Computer Networking Students and more Exams Cryptography and System Security in PDF only on Docsity! 1 Cork Institute of Technology Bachelor of Science (Honours) in Software Development & Computer Networking – Award (Bachelor of Science in Software Development and Computer Networking – Award) (NFQ – Level 8) Autumn 2005 Cryptography (Time: 2 Hours) Instructions: Answer any three questions. Each Question is worth 40 Marks. Note that 120 Marks = 100%. Examiners: Dr. D. Chambers Mr. P. O Connor Mr. T. Parslow Mr. V. Ryan Question 1 (a) Outline the AES/Rijndael Cipher. [9 Marks] (b) Describe the criteria that were used in the selection of a cipher as the Advanced Encryption Standard. [8 Marks] (c) Explain what is meant by the terms block cipher and stream cipher. [8 Marks] (d) Outline and discuss the one-time pad. [7 Marks] (e) Discuss the function of the S-Boxes in a typical cipher. [8 Marks] 2 Question 2 (a) Outline the RSA cipher. [5 Marks] (b) Suppose that RSA is being used. The parameters p,q and e have been chosen as 61, 157 and 3187 respectively. Complete the key generation by finding d. Use the Euclidean Algorithm. [9 Marks] Encrypt the plaintext 42 using the public key. Use the Fast exponentiation method. [8 Marks] (c) Discuss the main factoring algorithms, and the state of the art in factoring. As part of your discussion, explain the term MIPS-Years. [8 Marks] (d) Explain how RSA secret key computations can be speeded up using the Chinese Remainder Theorem. Some of the calculations/equations involved are dp= d mod (p-1) dq= d mod (q-1) Mp = C d p mod p Mq = C d q mod q [10 Marks] Question 3 (a) Detail the ECB mode of operation for encryption and decryption. [7 Marks] (b) Detail the strengths and weaknesses of the ECB mode. [6 Marks] (c) Detail the CTR mode of operation for encryption. [7 Marks] (d) What is the short-cycle problem? Give details. [7 Marks] (e) Does the short-cycle problem affect CTR mode? Why? [5 Marks] (f) List the strengths and weaknesses of CTR mode. [8 Marks]