UNIVERSITY OF MARYLAND DEPARTMENT OF ELECTRICAL AND COMPUTER ENGINEERING ENEE 459C Computer Security Instructor: Charalampos Papamanthou Homework 2 Out: 10/08/13 Due: 10/25/13 Instructions 1. Strictly adhere to the University of Maryland Code of Academic Integrity. 2. Type and submit your solutions as a pdf document at Canvas. Include your full name in the solutions document. Name the solutions document as x-hw2.pdf, where x is your last name. 3. No extensions will be given. Everything will be due at 11.59pm on 10/25/13. Problem 1 (20 points) You are given that 35 = 5 7 and that 3 5 ?? 2 7 = 1. Use the Chinese remainder theorem to compute 772 mod 35 : Explain why you cannot use the rule 772 mod 35 = 772 mod (35) mod 35, where (35) = (5 ?? 1)(7 ?? 1). Problem 2 (20 points) 1. What is the difference between public-key encryption and secret-key encryption? What is a certification authority? What is a digital certificate? 2. Suppose Mallory is responsible for storing all the public keys of the students that are currently enrolled at the University of Maryland. Namely, it keeps a list of mappings of (di; pki), where di is the directory identifier of student i and pki is the public key of student i. Suppose Bob, Alice and Eve are all students at the university. Bob wants to send a confidential message to Alice and asks Mallory for Alice’s public key. However Eve is really interested in learning what Bob wants to say to Alice. Eve happens to be very good friends with Mallory. Explain how Eve could collaborate with Mallory so that Eve eventually gets to decrypt Bob’s message to Alice. 3. Instead of using Mallory for managing public keys, Bob and Alice decide to setup their public keys with Verisign, Inc., a trusted certification authority. In order to arrange a meeting for the weekend, Bob exchanges with Alice brief text messages, using RSA encryption, as described in slide 5 of Lecture 8 (click here to access Lecture 8). Let pB and pA be the public keys of Bob and Alice…