Ask Question, Ask an Expert


Ask Computer Network & Security Expert

problem 1: problems for short answers

1) Suppose that f: {0, 1}n → Zp where p is a large prime and n > p. Prove that f(x) = gx

(mod p) is not second pre-image resistant, where g is a generator of Zp. What is the security assumption you use, if to make it pre-image resistant.

2) Show that the active CCA against ElGamal encryption given in the lecture does not work when against the Cramer-Shoup encryption.

3) Show that the RSA encryption is insecure against a chosen ciphertext attack. In particular, given a ciphertext y, describe how to choose a ciphertext y' such that knowledge of the plaintext x' = DK(y') allows the attacker to determine x = DK(y).

4) Show that the RSA encryption is not semantically secure. Provide a game between an adversary A and a simulator (or challenger) B.

5) Let p = 151. Choose a generator for GF(143)*. Choose an appropriate private and ephemeral key. Perform the following on the message m = 113, or the next appropriate message:

(a) Encrypt m using ElGamal.
(b) Signing m using ElGamal.

You can use Pari/GP.

6) Assume an elliptic curve with points whose coordinates P = (x; y) satisfy the following congruence y2 = x3 + x mod 23. Given two points P = (1; 5) and Q = (9; 5), what are the points P + Q, P + P, and Q + Q?

7) Show that if the Gap Die-Hellman Problem is easy, then the Cha-Cheon signature scheme will be broken.

8) Show that the Cha-Cheon signature scheme will be broken if the Gap Die-Hellman Problem is solved in a signature forgery reduction by forking. Do not need to give a formal proof.

9) Describe the Bilinear Die-Hellman (BDH) Problem and describe why the Boneh-Franklin identity-based encryption scheme is broken if the BDH problem is easy. Is the Basic version of Boneh-Franklin identity-based encryption scheme CCA secure? Why?

problem 2: Design a communication protocol based on identity-based cryptography

Alice and Bob are located at di erent locations and want to communicate securely by the computer network. Their identities are public. They are equipped with the Bone-Franklin ID-based encryption scheme, the Cha-Cheon signature scheme and AES, which should be properly used in their communication protocol. Your protocol must meet the following requirements:

A) Key generation: They need to generate their keys. Describe it in detail. Include all parties who have to be involved in key generation.

B) Mutual Authentication: They should know the origin of a message, i.e., who sent the message.

C) Con dentiality: Messages must be protected and should not be disclosed to others.

D) Session Key Establishment: Alice and Bob need a symmetric session for each of their communication session.

Your protocol should have three steps:

Step 1: Alice sends a message to Bob.

Upon receiving this message, Bob is convinced that the message comes from Alice and no one else apart from Alice has seen the message.

Step 2: Bob responds:

Upon receiving the response, Alice is convinced that Bob has received her previous message and has read the content. She is also sure that Bob's response must come from Bob and no one else apart from Bob has seen it.

Step 3: They communicate each other with a symmetric session key, which was established in Steps 1 and 2. Provide detailed protocol steps.

The protocol will be assessed in terms of these requirements. Describe how these requirements are met in your protocol. You must provide the algorithms (math) in your protocol.

Computer Network & Security, Computer Science

  • Category:- Computer Network & Security
  • Reference No.:- M91884

Have any Question? 

Related Questions in Computer Network & Security

Cryptography assignment1 decrypt the following message

Cryptography Assignment 1. Decrypt the following message. Assume direct letter substitution. blf szev yvvm z tivzg xozhh. I drhs blf zoo hfxxvhh zmw hzkkrmvhh. 2. Research the RSA cryptographic algorithm. a. If the Publi ...

Assignment give an answer to the following topicswhat are

Assignment: Give an answer to the following topics: What are the security issues with wireless LANs and WANs in a data processing environment? What are the recommended solutions to the issues identified? What are the sec ...

Lab assignment- assessment questions1 explain the two

Lab Assignment- Assessment Questions 1. Explain the two different types of attacks that can be performed in Cain and Abel to crack user account passwords. Which do you think is the most effective and why? 2. Compare and ...

Question 1which of the following must you do before ip

Question 1 Which of the following must you do before IP source guard can be used on a switch port? (Select 2 choices.) A) Enable IP routing on the switch port. B) Enable DHCP snooping on the switch. C) Configure static I ...

Assignment descriptionassignment overviewfor this

Assignment Description Assignment Overview For this assignment you will evaluate a Network Security Software. Marks will be awarded based on the sophistication and the difficulties the demonstration explored. Your task i ...

Questions1 describe three factors that help to influence

Questions: 1. Describe three factors that help to influence our nation's focus on natural or man-made disasters. 2. What issues have been raised concerning some of the authorities granted to government agencies in the PA ...

Your assignment must be in microsoft word formatnote your

Your assignment must be in Microsoft Word format Note: Your assignment must be in Microsoft Word format, and must be submitted electronically by the due date via the Moodle website Question 1: Firewall Rule Design The fo ...

Iriss smartphone beeped frowning she glanced at the screen

Iris's smartphone beeped. Frowning, she glanced at the screen, expecting to see another junk e-mail. "We've really got to do something about the spam!" she muttered to herself. She scanned the header of the message. "Uh- ...

This assignment assumes that you are one of the network

This assignment assumes that you are one of the Network Engineer of a small Company which has two branch offices, Branch 1 (BR1), Branch 2 (BR2) and a Headquarter (HQ). The branches need to be interconnected to the Headq ...

Assignmentwan technologies paper research point-to-point

Assignment WAN Technologies Paper: Research Point-to-Point (dedicated), Packet Switched, and Circuit Switched WAN protocols/circuits/types. Define each protocol and describe at least two data transmission technologies as ...

  • 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

WalMart Identification of theory and critical discussion

Drawing on the prescribed text and/or relevant academic literature, produce a paper which discusses the nature of group

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