Week 4 Tutorial Sheet
Public Key Encryption: Part 1
IMPORTANT NOTES: Study lecture materials at least 1 hour and prepare Question 1-3 prior to the tutorial session. Prepared questions will be discussed in the tutorial session.
1. What are the essential ingredients of an asymmetric / public-key cipher?
Copyright By PowCoder代写 加微信 powcoder
2. What is the difference between the public key and the private (secret) key? Why the public-key cryptosystem is still secure even after giving the public key to the attacker?
3. Write the following composite numbers as a multiplication of their prime factors.
(a) 12 (b) 78 (c) 99
4. Complete the following modular arithmetic operations and determine the result:
(a) (12+8) mod 6 (b) (2×12) mod 6
(c) (20 + 125) mod 5 (d) (20 − 35) mod 5 (e) 104 mod 3
(f) 10−1 mod 31 (g) 13−1 mod 19
5. Using the “Square and Multiply” modular exponentiation algorithm calculate the following:
(a) 7156 mod 11 (b) 5866 mod 31
程序代写 CS代考 加微信: powcoder QQ: 1823890830 Email: powcoder@163.com