Homework5 Answers - CNT4704 (Fall 2010) Homework 5 Solution...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
CNT4704 (Fall 2010) Homework 5 Solution 1. (25 points) Suppose N people want to communicate with each of N-1 other people using symmetric key encryption. All communication between any two people, i and j, is visible to all other people in this group of N, and no other people in this group should be able to decode their comunication. How many keys are required in this system as a whole? Now suppose that public key encryption is used. How many keys are required in this case? Answer: Any pair of persons needs one symmetric key for encryption. This means the N nodes form a completely connected graph. Each person (node) has N-1 links to others, thus there are overall N(N-1)/2 links in this graph, which means N(N-1)/2 keys are needed. When using public key encryption, each person needs his own public/private key pairs. Thus overall N pairs of public/private key pairs are needed. 2. (25 points) Using the Cesear cipher introduced in lecture, decode the message "JU'T UJNF OPX.". Also show what is the shifting key used here? Using the same
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 2

Homework5 Answers - CNT4704 (Fall 2010) Homework 5 Solution...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online