Ask Question, Ask an Expert


Ask Computer Engineering Expert

1. Alice and Bob are sending a message m to each other

a) Give one method to attain confidentiality for m.

b) Give one method to attain integrity but NOT confidentiality for m

2. Computer B needs a user name and password for every login. User A requires to log on over the Internet. One solution is to send in the user name and the password in clear text.

a) What is the security vulnerability of this solution?

b) Design a better solution. Draw the diagram only to describe message exchange and content of each message.

3. A stream cipher is used to encrypt. The plain text m1 is 10101010, the pseudo random k is: 01101011

a) What is the cipher text c1? (Demonstrate the whole mathematical steps)

b) If another plain text m2 11100010 is encrypted with the same pseudo random number k andgenerate cipher text c2, what useful information about m1 and m2 can you extract from c1 and c2? (Demonstrate the entire mathematical steps)

4. B receives a financial transaction request message m from someone claims to be A. The message is encrypted with a shared security key k which only A and B know. Suppose the encryption is absolutely unbreakable.

a) Can B be reasonably sure that message is generated by A? Why?

b) If B shows another person C that B could use the key k to decrypt the message, could C be reasonably sure that message is generated by A? Whey?

c) Design a different protocol so that when B receives a message m from the real A, both B and C could be reasonably sure that the message is indeed generated by A?

5. If the time to encrypt a message m using a 64-bit secret key k algorithm is T, use the big-O notation to answer the following problems:

a) How to decrypt the message with brutal force? What is the amount of time required?

b) If length of the key is doubled, what is the amount of time needed to decrypt message with brutal force? Why?

6. With CBC encryption, message blocks m1-m2-m3-m4 are encrypted into c1-c2-c3-c4. Now if a hacker intercepts cipher text and retransmits c1-c3-c3-c4, what would be the “plain text” blocks being decrypted into? (Demonstrate all detail calculations)

Computer Engineering, Engineering

  • Category:- Computer Engineering
  • Reference No.:- M91996

Have any Question? 

Related Questions in Computer Engineering

1 a paged memory system has 16-bit virtual addresses and

1. A paged memory system has 16-bit virtual addresses and pages that are 1024 locations long. How many entries must the page table have? 2. If virtual addresses are V bits long, physical addresses are A bits long, the pa ...

Coursemultimedia systems developmentquestionsq1 identify

Course: (Multimedia Systems Development) Questions: Q.1 Identify and explain the three major interrelated tasks for creating 3-D animation. Q.2 Identify and explain the advantages of sampled sound and synthesized sound. ...

1 write findmin and findmax methods for the avltree class2

1. Write FindMin and FindMax methods for the AVLTree class. 2. Using the Timing class, compare the times for the methods implemented in Exercise 1 to the same methods in the BinarySearchTree class. Your test program shou ...

1 what is an internet what is the internet2 why are

1. What is an internet? What is the Internet? 2. Why are protocols needed? 3. In a LAN with a link-layer switch (Figure 1.8b), Host 1 wants to send a message to Host 3. Since communication is through the link-layer switc ...

1 what is a discontiguous network why does it pose

1. What is a discontiguous network? Why does it pose challenges for a network designer? 2. Why is it important to characterize a network's logical topology and not just its physical topology? What information does a logi ...

1 x509 is a good security protocol study x509 and discuss

1. X.509 is a good security protocol. Study X.509 and discuss how it differs from S-HTTP and IP Sec. 2. SSL3.0 has been transformed into TLS 1.0. Study the TLS protocol specifications and show how all are met by SSL. The ...

A show that the normalized uniform periodic b -splines

a. Show that the normalized uniform periodic B -splines satisfy b. If an object of uniform density is approximated by the polygon obtained by joining the adjacent control points by straight lines, find the expressions fo ...

Network design for schoola network has to be designed for a

Network Design for Schoola network has to be designed for a school. There are100 computers in the school. And has 5 Labs each of them consisted of 31 computersThe users in the lab should belong to a single domain and rec ...

1 provide junit test class taxreturntest with three test

1. Provide JUnit test class TaxReturnTest with three test methods that test different tax situations for the TaxReturn class in Chapter 5. 2. Write methods that show the letters H, E, L, O on the graphics window, where t ...

1 evaluate the four basic linked list operations for a

1. Evaluate the four basic linked list operations for a sorted doubly linked list and indicate the worst case time-complexities of each. 2. Evaluate the worst case time-complexity for the search operation on a doubly lin ...

  • 4,153,160 Questions Asked
  • 13,132 Experts
  • 2,558,936 Questions Answered

Ask Experts for help!!

Looking for Assignment Help?

Start excelling in your Courses, Get help with Assignment

Write us your full requirement for evaluation and you will receive response within 20 minutes turnaround time.

Ask Now Help with Problems, Get a Best Answer

Section onea in an atwood machine suppose two objects of

SECTION ONE (a) In an Atwood Machine, suppose two objects of unequal mass are hung vertically over a frictionless

Part 1you work in hr for a company that operates a factory

Part 1: You work in HR for a company that operates a factory manufacturing fiberglass. There are several hundred empl

Details on advanced accounting paperthis paper is intended

DETAILS ON ADVANCED ACCOUNTING PAPER This paper is intended for students to apply the theoretical knowledge around ac

Create a provider database and related reports and queries

Create a provider database and related reports and queries to capture contact information for potential PC component pro

Describe what you learned about the impact of economic

Describe what you learned about the impact of economic, social, and demographic trends affecting the US labor environmen