Elements of Cryptography and Computer and Networking Security Computer Science 134 (COMPSCI 134) Fall 2016 Instructor: Karim ElDefrawy

Size: px
Start display at page:

Download "Elements of Cryptography and Computer and Networking Security Computer Science 134 (COMPSCI 134) Fall 2016 Instructor: Karim ElDefrawy"

Transcription

1 Elements of Cryptography and Computer and Networking Security Computer Science 134 (COMPSCI 134) Fall 2016 Instructor: Karim ElDefrawy Homework 2 Due: Friday, 10/28/2016 at 11:55pm PT Will be posted on Monday, 10/31/2016 Full Name: UCI ID Number: Sources: Guidelines: Use any word processor (or handwrite and scan your answers). Upload your solutions as a PDF to the associated EEE dropbox (labeled CS134: Homework 2 ). No late submission will be accepted into the EEE dropbox. The solution to the homework will be posted on Monday 10/31/2016, no late submission (even via ) will be accepted after posting of the solution. No collaboration is allowed. The only people you may ask for help are the TA and professor for the course. Copying, paraphrasing or copying answers from the internet or other sources is not allowed, and to do so would be a violation of academic honesty. You must list any sources you used to arrive at your answers (e.g., reference books, Wikipedia etc). Warning: any submission not following the above guidelines may receive a score of zero.

2 1 [5 pts total] Multiple Choice Questions There is only one correct answer for each of the following question. Answer justification is not required. 1. Which of the following is a NON-cryptographic property of a good hash function? A. One-way-ness B. Weak-collision-resistance C. Strong-collision-resistance D. Arbitrary-length input 2. What is the correct comparison of SHA-1 and MD5? A. MD5 is more secure than SHA-1 B. SHA-1 is more computationally expensive than MD5 C. MD5 does not work on an extremely large input (> 2 64 bits) while SHA-1 does D. Neither can be used as an encryption function 3. Which of the following is NOT a property of a group? A. Closure B. Distribution C. Identity D. Inverse 4. Which of the following is NOT an Abelian group? A. (Z N, modular multiplication) B. (Z, addition) C. (set of 5x5 non-singular real matrices, matrix addition) D. (set of 5x5 non-singular real matrices, matrix multiplication) 5. Which of the following is a subgroup of Z 13 under modular multiplication? A. {2, 7} B. {1, 2, 7, 12} C. {1, 6, 12} D. {1, 5, 10, 11} 6. What security service CANNOT be provided by a digital signature? A. Availability B. Integrity C. Non-repudiation D. Authentication Page 2

3 7. The security of Diffie-Hellman key exchange relies on which assumption? A. It is computationally infeasible to compute a GCD of two large numbers. B. It is computationally infeasible to compute an inverse modulo prime p. C. It is computationally infeasible to test whether a large number is prime. D. It is computationally infeasible to solve the discrete log problem. E. All of the above 8. What is the objective of Diffie-Hellman key exchange? A. to protect encrypted data from man-in-the-middle attack B. to perform mutual authentication on both sides C. to prove to another party that one holds a secret key without revealing it D. to establish a shared secret key on both sides 9. The security of RSA encryption relies on which assumption? A. It is computationally infeasible to compute a GCD of two large numbers. B. It is computationally infeasible to factor a large number. C. It is computationally infeasible to test whether a large number is prime. D. It is computationally infeasible to compute a square modulo n. E. All of the above 10. Which of the following scheme is an example of zero-knowledge proof? A. Fiat-Shamir identification B. El Gamal encryption C. RSA signature D. Diffie-Hellman key exchange E. All of the above Page 3

4 2 [5 pts total] Fill In The Blanks 1. The digest size of SHA-1 is bits. 2. The block size of MD5 is bits. 3. A prefix MAC construction, i.e. H(K AB m), cannot provide the integrity of a message because 4. The inverse of 9 in Z 11 is. 5. ord(9) in Z 11 =. 6. If α is a primitive element in Z p for a prime p, this means ord(α) equals. 7. Square-and-Multiply algorithm can be used to compute 5 8 mod 9 in iterations. 8. The Digital Signature Standard (DSS) is a variant of signature scheme. 9. Extended Euclidean Algorithm can be used to speed-up the calculation of in RSA Encryption, given a public exponent (e) and the modulus factor (p and q). 10. In RSA signature scheme, a signature of a message m can be created by computing y = (m d mod n) whereas the signature can be verified by. Assume d is the secret key, e is the public key, and n is a product of two large prime numbers.. Page 4

5 3 [4 pts] Birthday Paradox Suppose the California DMV comes up with a new license plate with a special serial number format. This serial number format consists of only 3 letters: first two being a digit (0 to 9) and last one being an English uppercase letter (A to Z). Each serial number is randomly generated when issued. (a) Suppose Alice and Bob apply for this new license plate. What is the probability that both of them receive the same plate number? (b) Suppose the California DMV wants to ensure that the probability that at least two license plates have the same number is less than 1%. What is the maximum number of this type of license plates that they can issue? (c) Suppose the California DMV wants to issue exactly 50 license plates. How many more DIGITS should be added at the end of this serial number format in order to ensure that the probability that at least two license plates have the same number is still less than 1%. Page 5

6 4 [4 pts] Groups and Subgroups (a) List all elements in the group Z 10. (b) Show that the group (Z 10 under modular multiplication) is cyclic. (c) Suppose S = {1, 3, 9}. Is S a subgroup of Z 10 under modular multiplication? If it is, show that all subgroup properties hold for S. If it is not, briefly explain why not. (d) Suppose S = {1, 3, 7}. Is S a subgroup of Z 10 under modular multiplication? If it is, show that all subgroup properties hold for S. If it is not, briefly explain why not. Page 6

7 5 [4 pts] RSA Assume the following RSA parameters: p = 13, q = 5, d = 29, C = 7 (a) Use Chinese Remainder Theorem to find the value of plaintext M. Show your work. (b) Use Extended Euclidean Algorithm to find the value of public exponent e. Show your work. Page 7

8 6 [3 pts] 3-Party Diffie-Hellman Recall from the lecture that the Diffie-Hellman protocol allows two parties to establish a shared secret key. However, the use of Diffie-Hellman is not limited to only two parties. In fact, the Diffie-Hellman scheme can be extended to support the key establishment between any number of parties. Describe how to establish a shared secret key between three parties based on the Diffie-Hellman key exchange scheme. (Note that minimizing communication rounds and bandwidth consumed between the parties in this case is not a concern.) Page 8

9 7 [3 pts] Randomness in El Gamal s Scheme Suppose Alice wants to encrypt two messages using El Gamal Public Key Cryptosystem. However, she is lazy and does not want to generate a new random number for the second encryption. Thus, she applies the same random number (which is only secret to her) for both encryptions. Suppose Eve learns both ciphertexts and one of the plaintext message. Show that Eve can efficiently learn the value of the other plaintext message as well. Also, you can assume that the same public- and private-key pair is used for both encryptions. Page 9

10 8 [3 pts] Fiat-Shamir One of the requirements of the Fiat-Shamir identification protocol is to have a trusted-third party generate n and keep its factors (prime p and q) secret from the prover and verifier. Suppose the verifier knows one of those two factors. Explain how the verifier can learn the secret of the prover when Fiat-Shamir identification protocol is run by both sides. (Hint: you may assume it is computationally feasible to compute a 1/2 mod b ONLY when b is a prime less than n.) Page 10

Elements of Cryptography and Computer and Network Security Computer Science 134 (COMPSCI 134) Fall 2016 Instructor: Karim ElDefrawy

Elements of Cryptography and Computer and Network Security Computer Science 134 (COMPSCI 134) Fall 2016 Instructor: Karim ElDefrawy Elements of Cryptography and Computer and Network Security Computer Science 134 (COMPSCI 134) Fall 2016 Instructor: Karim ElDefrawy Homework 3 Due: Monday, 11/28/2016 at 11:55pm PT Solution: Will be posted

More information

Elements of Cryptography and Computer and Network Security Computer Science 134 (COMPSCI 134) Fall 2016 Instructor: Karim ElDefrawy

Elements of Cryptography and Computer and Network Security Computer Science 134 (COMPSCI 134) Fall 2016 Instructor: Karim ElDefrawy Elements of Cryptography and Computer and Network Security Computer Science 134 (COMPSCI 134) Fall 2016 Instructor: Karim ElDefrawy Homework 3 Due: Monday, 11/28/2016 at 11:55pm PT Solution: Will be posted

More information

Winter 2018 CS134: Computer and Network Security Homework 2 Due: 02/26/18, 11:59pm

Winter 2018 CS134: Computer and Network Security Homework 2 Due: 02/26/18, 11:59pm Winter 2018 CS134: Computer and Network Security Homework 2 Due: 02/26/18, 11:59pm Full Name: UCI ID Number: Sources: Guidelines: Use any word processor. Write your Name, UCInetID and Student ID on each

More information

Public Key Algorithms

Public Key Algorithms Public Key Algorithms 1 Public Key Algorithms It is necessary to know some number theory to really understand how and why public key algorithms work Most of the public key algorithms are based on modular

More information

CS 161 Computer Security

CS 161 Computer Security Raluca Popa Spring 2018 CS 161 Computer Security Homework 2 Due: Wednesday, February 14, at 11:59pm Instructions. This homework is due Wednesday, February 14, at 11:59pm. No late homeworks will be accepted.

More information

Dr. Jinyuan (Stella) Sun Dept. of Electrical Engineering and Computer Science University of Tennessee Fall 2010

Dr. Jinyuan (Stella) Sun Dept. of Electrical Engineering and Computer Science University of Tennessee Fall 2010 CS 494/594 Computer and Network Security Dr. Jinyuan (Stella) Sun Dept. of Electrical Engineering and Computer Science University of Tennessee Fall 2010 1 Public Key Cryptography Modular Arithmetic RSA

More information

CS Computer Networks 1: Authentication

CS Computer Networks 1: Authentication CS 3251- Computer Networks 1: Authentication Professor Patrick Traynor 4/14/11 Lecture 25 Announcements Homework 3 is due next class. Submit via T-Square or in person. Project 3 has been graded. Scores

More information

CSC 474/574 Information Systems Security

CSC 474/574 Information Systems Security CSC 474/574 Information Systems Security Topic 2.5 Public Key Algorithms CSC 474/574 Dr. Peng Ning 1 Public Key Algorithms Public key algorithms covered in this class RSA: encryption and digital signature

More information

Outline. Public Key Cryptography. Applications of Public Key Crypto. Applications (Cont d)

Outline. Public Key Cryptography. Applications of Public Key Crypto. Applications (Cont d) Outline AIT 682: Network and Systems Security 1. Introduction 2. RSA 3. Diffie-Hellman Key Exchange 4. Digital Signature Standard Topic 5.2 Public Key Cryptography Instructor: Dr. Kun Sun 2 Public Key

More information

CSCI 454/554 Computer and Network Security. Topic 5.2 Public Key Cryptography

CSCI 454/554 Computer and Network Security. Topic 5.2 Public Key Cryptography CSCI 454/554 Computer and Network Security Topic 5.2 Public Key Cryptography Outline 1. Introduction 2. RSA 3. Diffie-Hellman Key Exchange 4. Digital Signature Standard 2 Introduction Public Key Cryptography

More information

Introduction to Cryptography Lecture 7

Introduction to Cryptography Lecture 7 Introduction to Cryptography Lecture 7 El Gamal Encryption RSA Encryption Benny Pinkas page 1 1 Public key encryption Alice publishes a public key PK Alice. Alice has a secret key SK Alice. Anyone knowing

More information

Outline. CSCI 454/554 Computer and Network Security. Introduction. Topic 5.2 Public Key Cryptography. 1. Introduction 2. RSA

Outline. CSCI 454/554 Computer and Network Security. Introduction. Topic 5.2 Public Key Cryptography. 1. Introduction 2. RSA CSCI 454/554 Computer and Network Security Topic 5.2 Public Key Cryptography 1. Introduction 2. RSA Outline 3. Diffie-Hellman Key Exchange 4. Digital Signature Standard 2 Introduction Public Key Cryptography

More information

Lecture 2 Applied Cryptography (Part 2)

Lecture 2 Applied Cryptography (Part 2) Lecture 2 Applied Cryptography (Part 2) Patrick P. C. Lee Tsinghua Summer Course 2010 2-1 Roadmap Number theory Public key cryptography RSA Diffie-Hellman DSA Certificates Tsinghua Summer Course 2010 2-2

More information

Information Security. message M. fingerprint f = H(M) one-way hash. 4/19/2006 Information Security 1

Information Security. message M. fingerprint f = H(M) one-way hash. 4/19/2006 Information Security 1 Information Security message M one-way hash fingerprint f = H(M) 4/19/2006 Information Security 1 Outline and Reading Digital signatures Definition RSA signature and verification One-way hash functions

More information

Chapter 9 Public Key Cryptography. WANG YANG

Chapter 9 Public Key Cryptography. WANG YANG Chapter 9 Public Key Cryptography WANG YANG wyang@njnet.edu.cn Content Introduction RSA Diffie-Hellman Key Exchange Introduction Public Key Cryptography plaintext encryption ciphertext decryption plaintext

More information

Public Key Algorithms

Public Key Algorithms Public Key Algorithms CS 472 Spring 13 Lecture 6 Mohammad Almalag 2/19/2013 Public Key Algorithms - Introduction Public key algorithms are a motley crew, how? All hash algorithms do the same thing: Take

More information

Public Key Algorithms

Public Key Algorithms CSE597B: Special Topics in Network and Systems Security Public Key Cryptography Instructor: Sencun Zhu The Pennsylvania State University Public Key Algorithms Public key algorithms RSA: encryption and

More information

CS 161 Computer Security

CS 161 Computer Security Popa & Wagner Spring 2016 CS 161 Computer Security Discussion 5 Week of February 19, 2017 Question 1 Diffie Hellman key exchange (15 min) Recall that in a Diffie-Hellman key exchange, there are values

More information

Digital Signatures. KG November 3, Introduction 1. 2 Digital Signatures 2

Digital Signatures. KG November 3, Introduction 1. 2 Digital Signatures 2 Digital Signatures KG November 3, 2017 Contents 1 Introduction 1 2 Digital Signatures 2 3 Hash Functions 3 3.1 Attacks.................................... 4 3.2 Compression Functions............................

More information

Encryption. INST 346, Section 0201 April 3, 2018

Encryption. INST 346, Section 0201 April 3, 2018 Encryption INST 346, Section 0201 April 3, 2018 Goals for Today Symmetric Key Encryption Public Key Encryption Certificate Authorities Secure Sockets Layer Simple encryption scheme substitution cipher:

More information

Introduction to Cryptography Lecture 7

Introduction to Cryptography Lecture 7 Introduction to Cryptography Lecture 7 Public-Key Encryption: El-Gamal, RSA Benny Pinkas page 1 1 Public key encryption Alice publishes a public key PK Alice. Alice has a secret key SK Alice. Anyone knowing

More information

Key Exchange. References: Applied Cryptography, Bruce Schneier Cryptography and Network Securiy, Willian Stallings

Key Exchange. References: Applied Cryptography, Bruce Schneier Cryptography and Network Securiy, Willian Stallings Key Exchange References: Applied Cryptography, Bruce Schneier Cryptography and Network Securiy, Willian Stallings Outlines Primitives Root Discrete Logarithm Diffie-Hellman ElGamal Shamir s Three Pass

More information

Distributed Systems. 26. Cryptographic Systems: An Introduction. Paul Krzyzanowski. Rutgers University. Fall 2015

Distributed Systems. 26. Cryptographic Systems: An Introduction. Paul Krzyzanowski. Rutgers University. Fall 2015 Distributed Systems 26. Cryptographic Systems: An Introduction Paul Krzyzanowski Rutgers University Fall 2015 1 Cryptography Security Cryptography may be a component of a secure system Adding cryptography

More information

CS 161 Computer Security

CS 161 Computer Security Popa & Wagner Spring 2016 CS 161 Computer Security Midterm 2 Print your name:, (last) (first) I am aware of the Berkeley Campus Code of Student Conduct and acknowledge that academic misconduct will be

More information

Kurose & Ross, Chapters (5 th ed.)

Kurose & Ross, Chapters (5 th ed.) Kurose & Ross, Chapters 8.2-8.3 (5 th ed.) Slides adapted from: J. Kurose & K. Ross \ Computer Networking: A Top Down Approach (5 th ed.) Addison-Wesley, April 2009. Copyright 1996-2010, J.F Kurose and

More information

Overview. Public Key Algorithms I

Overview. Public Key Algorithms I Public Key Algorithms I Dr. Arjan Durresi Louisiana State University Baton Rouge, LA 70810 Durresi@csc.lsu.Edu These slides are available at: http://www.csc.lsu.edu/~durresi/csc4601-04/ Louisiana State

More information

CSE 127: Computer Security Cryptography. Kirill Levchenko

CSE 127: Computer Security Cryptography. Kirill Levchenko CSE 127: Computer Security Cryptography Kirill Levchenko October 24, 2017 Motivation Two parties want to communicate securely Secrecy: No one else can read messages Integrity: messages cannot be modified

More information

Cryptographic Hash Functions

Cryptographic Hash Functions ECE458 Winter 2013 Cryptographic Hash Functions Dan Boneh (Mods by Vijay Ganesh) Previous Lectures: What we have covered so far in cryptography! One-time Pad! Definition of perfect security! Block and

More information

Other Topics in Cryptography. Truong Tuan Anh

Other Topics in Cryptography. Truong Tuan Anh Other Topics in Cryptography Truong Tuan Anh 2 Outline Public-key cryptosystem Cryptographic hash functions Signature schemes Public-Key Cryptography Truong Tuan Anh CSE-HCMUT 4 Outline Public-key cryptosystem

More information

Chapter 9. Public Key Cryptography, RSA And Key Management

Chapter 9. Public Key Cryptography, RSA And Key Management Chapter 9 Public Key Cryptography, RSA And Key Management RSA by Rivest, Shamir & Adleman of MIT in 1977 The most widely used public-key cryptosystem is RSA. The difficulty of attacking RSA is based on

More information

TECHNISCHE UNIVERSITEIT EINDHOVEN Faculty of Mathematics and Computer Science Exam Cryptology, Tuesday 31 October 2017

TECHNISCHE UNIVERSITEIT EINDHOVEN Faculty of Mathematics and Computer Science Exam Cryptology, Tuesday 31 October 2017 Faculty of Mathematics and Computer Science Exam Cryptology, Tuesday 31 October 2017 Name : TU/e student number : Exercise 1 2 3 4 5 6 total points Notes: Please hand in this sheet at the end of the exam.

More information

Introduction. CSE 5351: Introduction to cryptography Reading assignment: Chapter 1 of Katz & Lindell

Introduction. CSE 5351: Introduction to cryptography Reading assignment: Chapter 1 of Katz & Lindell Introduction CSE 5351: Introduction to cryptography Reading assignment: Chapter 1 of Katz & Lindell 1 Cryptography Merriam-Webster Online Dictionary: 1. secret writing 2. the enciphering and deciphering

More information

The most important development from the work on public-key cryptography is the digital signature. Message authentication protects two parties who

The most important development from the work on public-key cryptography is the digital signature. Message authentication protects two parties who 1 The most important development from the work on public-key cryptography is the digital signature. Message authentication protects two parties who exchange messages from any third party. However, it does

More information

Cryptographic Systems

Cryptographic Systems CPSC 426/526 Cryptographic Systems Ennan Zhai Computer Science Department Yale University Recall: Lec-10 In lec-10, we learned: - Consistency models - Two-phase commit - Consensus - Paxos Lecture Roadmap

More information

CSC/ECE 774 Advanced Network Security

CSC/ECE 774 Advanced Network Security Computer Science CSC/ECE 774 Advanced Network Security Topic 2. Network Security Primitives CSC/ECE 774 Dr. Peng Ning 1 Outline Absolute basics Encryption/Decryption; Digital signatures; D-H key exchange;

More information

Cryptographic protocols

Cryptographic protocols Cryptographic protocols Lecture 3: Zero-knowledge protocols for identification 6/16/03 (c) Jussipekka Leiwo www.ialan.com Overview of ZK Asymmetric identification techniques that do not rely on digital

More information

RSA. Public Key CryptoSystem

RSA. Public Key CryptoSystem RSA Public Key CryptoSystem DIFFIE AND HELLMAN (76) NEW DIRECTIONS IN CRYPTOGRAPHY Split the Bob s secret key K to two parts: K E, to be used for encrypting messages to Bob. K D, to be used for decrypting

More information

L13. Reviews. Rocky K. C. Chang, April 10, 2015

L13. Reviews. Rocky K. C. Chang, April 10, 2015 L13. Reviews Rocky K. C. Chang, April 10, 2015 1 Foci of this course Understand the 3 fundamental cryptographic functions and how they are used in network security. Understand the main elements in securing

More information

P2_L8 - Hashes Page 1

P2_L8 - Hashes Page 1 P2_L8 - Hashes Page 1 Reference: Computer Security by Stallings and Brown, Chapter 21 In this lesson, we will first introduce the birthday paradox and apply it to decide the length of hash, in order to

More information

Introduction to Cryptography and Security Mechanisms: Unit 5. Public-Key Encryption

Introduction to Cryptography and Security Mechanisms: Unit 5. Public-Key Encryption Introduction to Cryptography and Security Mechanisms: Unit 5 Public-Key Encryption Learning Outcomes Explain the basic principles behind public-key cryptography Recognise the fundamental problems that

More information

Public Key Cryptography and RSA

Public Key Cryptography and RSA Public Key Cryptography and RSA Major topics Principles of public key cryptosystems The RSA algorithm The Security of RSA Motivations A public key system is asymmetric, there does not have to be an exchange

More information

Public Key Cryptography and the RSA Cryptosystem

Public Key Cryptography and the RSA Cryptosystem Public Key Cryptography and the RSA Cryptosystem Two people, say Alice and Bob, would like to exchange secret messages; however, Eve is eavesdropping: One technique would be to use an encryption technique

More information

Introduction to Cryptography. Lecture 6

Introduction to Cryptography. Lecture 6 Introduction to Cryptography Lecture 6 Benny Pinkas page 1 1 Data Integrity, Message Authentication Risk: an active adversary might change messages exchanged between Alice and Bob M Alice M M M Bob Eve

More information

Cryptography (DES+RSA) by Amit Konar Dept. of Math and CS, UMSL

Cryptography (DES+RSA) by Amit Konar Dept. of Math and CS, UMSL Cryptography (DES+RSA) by Amit Konar Dept. of Math and CS, UMSL Transpositional Ciphers-A Review Decryption 1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8 Encryption 1 2 3 4 5 6 7 8 A G O O D F R I E N D I S A T R E

More information

Chapter 8 Security. Computer Networking: A Top Down Approach. 6 th edition Jim Kurose, Keith Ross Addison-Wesley March 2012

Chapter 8 Security. Computer Networking: A Top Down Approach. 6 th edition Jim Kurose, Keith Ross Addison-Wesley March 2012 Chapter 8 Security A note on the use of these ppt slides: We re making these slides freely available to all (faculty, students, readers). They re in PowerPoint form so you see the animations; and can add,

More information

ח'/סיון/תשע "א. RSA: getting ready. Public Key Cryptography. Public key cryptography. Public key encryption algorithms

ח'/סיון/תשע א. RSA: getting ready. Public Key Cryptography. Public key cryptography. Public key encryption algorithms Public Key Cryptography Kurose & Ross, Chapters 8.28.3 (5 th ed.) Slides adapted from: J. Kurose & K. Ross \ Computer Networking: A Top Down Approach (5 th ed.) AddisonWesley, April 2009. Copyright 19962010,

More information

CS669 Network Security

CS669 Network Security UNIT II PUBLIC KEY ENCRYPTION Uniqueness Number Theory concepts Primality Modular Arithmetic Fermet & Euler Theorem Euclid Algorithm RSA Elliptic Curve Cryptography Diffie Hellman Key Exchange Uniqueness

More information

Side-Channel Attacks on RSA with CRT. Weakness of RSA Alexander Kozak Jared Vanderbeck

Side-Channel Attacks on RSA with CRT. Weakness of RSA Alexander Kozak Jared Vanderbeck Side-Channel Attacks on RSA with CRT Weakness of RSA Alexander Kozak Jared Vanderbeck What is RSA? As we all know, RSA (Rivest Shamir Adleman) is a really secure algorithm for public-key cryptography.

More information

ENEE 459-C Computer Security. Message authentication

ENEE 459-C Computer Security. Message authentication ENEE 459-C Computer Security Message authentication Data Integrity and Source Authentication Encryption does not protect data from modification by another party. Why? Need a way to ensure that data arrives

More information

CS 161 Computer Security

CS 161 Computer Security Paxson Spring 2013 CS 161 Computer Security 3/14 Asymmetric cryptography Previously we saw symmetric-key cryptography, where Alice and Bob share a secret key K. However, symmetric-key cryptography can

More information

Public-Key Cryptography. Professor Yanmin Gong Week 3: Sep. 7

Public-Key Cryptography. Professor Yanmin Gong Week 3: Sep. 7 Public-Key Cryptography Professor Yanmin Gong Week 3: Sep. 7 Outline Key exchange and Diffie-Hellman protocol Mathematical backgrounds for modular arithmetic RSA Digital Signatures Key management Problem:

More information

A SIGNATURE ALGORITHM BASED ON DLP AND COMPUTING SQUARE ROOTS

A SIGNATURE ALGORITHM BASED ON DLP AND COMPUTING SQUARE ROOTS A SIGNATURE ALGORITHM BASED ON DLP AND COMPUTING SQUARE ROOTS Ounasser Abid 1 and Omar Khadir 2 1, 2 Laboratory of Mathematics, Cryptography and Mechanics, FSTM University Hassan II of Casablanca, Morocco

More information

CS 470 Spring Security. Mike Lam, Professor. a.k.a. Why on earth do Alice and Bob need to talk so much?!? Content taken from the following:

CS 470 Spring Security. Mike Lam, Professor. a.k.a. Why on earth do Alice and Bob need to talk so much?!? Content taken from the following: 50fb6be35f4c3105 9d4ed08fb86d8887 b746c452a9c9443b 15b22f450c76218e CS 470 Spring 2017 9df7031cdbff9d10 b700a92855f16328 5b757e66d2131841 62fedd7d9131e42e Mike Lam, Professor Security a.k.a. Why on earth

More information

Lecture 6 - Cryptography

Lecture 6 - Cryptography Lecture 6 - Cryptography CMPSC 443 - Spring 2012 Introduction Computer and Network Security Professor Jaeger www.cse.psu.edu/~tjaeger/cse443-s12 Question Setup: Assume you and I donʼt know anything about

More information

Channel Coding and Cryptography Part II: Introduction to Cryptography

Channel Coding and Cryptography Part II: Introduction to Cryptography Channel Coding and Cryptography Part II: Introduction to Cryptography Prof. Dr.-Ing. habil. Andreas Ahrens Communications Signal Processing Group, University of Technology, Business and Design Email: andreas.ahrens@hs-wismar.de

More information

What did we talk about last time? Public key cryptography A little number theory

What did we talk about last time? Public key cryptography A little number theory Week 4 - Friday What did we talk about last time? Public key cryptography A little number theory If p is prime and a is a positive integer not divisible by p, then: a p 1 1 (mod p) Assume a is positive

More information

Study Guide for the Final Exam

Study Guide for the Final Exam YALE UNIVERSITY DEPARTMENT OF COMPUTER SCIENCE CPSC 467b: Cryptography and Computer Security Handout #22 Professor M. J. Fischer April 30, 2005 1 Exam Coverage Study Guide for the Final Exam The final

More information

Lecture 30. Cryptography. Symmetric Key Cryptography. Key Exchange. Advanced Encryption Standard (AES) DES. Security April 11, 2005

Lecture 30. Cryptography. Symmetric Key Cryptography. Key Exchange. Advanced Encryption Standard (AES) DES. Security April 11, 2005 Lecture 30 Security April 11, 2005 Cryptography K A ciphertext Figure 7.3 goes here K B symmetric-key crypto: sender, receiver keys identical public-key crypto: encrypt key public, decrypt key secret Symmetric

More information

Uzzah and the Ark of the Covenant

Uzzah and the Ark of the Covenant Uzzah and the Ark of the Covenant And when they came to the threshing floor of Chidon, Uzzah put out his hand to take hold of the ark, for the oxen stumbled. 10 And the anger of the LORD was kindled against

More information

Applied Cryptography and Computer Security CSE 664 Spring 2018

Applied Cryptography and Computer Security CSE 664 Spring 2018 Applied Cryptography and Computer Security Lecture 13: Public-Key Cryptography and RSA Department of Computer Science and Engineering University at Buffalo 1 Public-Key Cryptography What we already know

More information

Security: Cryptography

Security: Cryptography Security: Cryptography Computer Science and Engineering College of Engineering The Ohio State University Lecture 38 Some High-Level Goals Confidentiality Non-authorized users have limited access Integrity

More information

Some Stuff About Crypto

Some Stuff About Crypto Some Stuff About Crypto Adrian Frith Laboratory of Foundational Aspects of Computer Science Department of Mathematics and Applied Mathematics University of Cape Town This work is licensed under a Creative

More information

(a) Symmetric model (b) Cryptography (c) Cryptanalysis (d) Steganography

(a) Symmetric model (b) Cryptography (c) Cryptanalysis (d) Steganography Code No: RR410504 Set No. 1 1. Write short notes on (a) Symmetric model (b) Cryptography (c) Cryptanalysis (d) Steganography 3. (a) Illustrate Diffie-hellman Key Exchange scheme for GF(P) [6M] (b) Consider

More information

Number Theory and RSA Public-Key Encryption

Number Theory and RSA Public-Key Encryption Number Theory and RSA Public-Key Encryption Dr. Natarajan Meghanathan Associate Professor of Computer Science Jackson State University E-mail: natarajan.meghanathan@jsums.edu CIA Triad: Three Fundamental

More information

Intro to Public Key Cryptography Diffie & Hellman Key Exchange

Intro to Public Key Cryptography Diffie & Hellman Key Exchange Intro to Public Key Cryptography Diffie & Hellman Key Exchange Course Summary Introduction Stream & Block Ciphers Block Ciphers Modes (ECB,CBC,OFB) Advanced Encryption Standard (AES) Message Authentication

More information

Public Key Cryptography

Public Key Cryptography Public Key Cryptography Giuseppe F. Italiano Universita` di Roma Tor Vergata italiano@disp.uniroma2.it Motivation Until early 70s, cryptography was mostly owned by government and military Symmetric cryptography

More information

Sankalchand Patel College of Engineering, Visnagar Department of Computer Engineering & Information Technology. Question Bank

Sankalchand Patel College of Engineering, Visnagar Department of Computer Engineering & Information Technology. Question Bank Sankalchand Patel College of Engineering, Visnagar Department of Computer Engineering & Information Technology Question Bank Subject: Information Security (160702) Class: BE Sem. VI (CE/IT) Unit-1: Conventional

More information

CSC 774 Network Security

CSC 774 Network Security CSC 774 Network Security Topic 2. Review of Cryptographic Techniques CSC 774 Dr. Peng Ning 1 Outline Encryption/Decryption Digital signatures Hash functions Pseudo random functions Key exchange/agreement/distribution

More information

Study Guide to Mideterm Exam

Study Guide to Mideterm Exam YALE UNIVERSITY DEPARTMENT OF COMPUTER SCIENCE CPSC 467b: Cryptography and Computer Security Handout #7 Professor M. J. Fischer February 20, 2012 Study Guide to Mideterm Exam For the exam, you are responsible

More information

Computer Security: Principles and Practice

Computer Security: Principles and Practice Computer Security: Principles and Practice Chapter 2 Cryptographic Tools First Edition by William Stallings and Lawrie Brown Lecture slides by Lawrie Brown Cryptographic Tools cryptographic algorithms

More information

Tuesday, January 17, 17. Crypto - mini lecture 1

Tuesday, January 17, 17. Crypto - mini lecture 1 Crypto - mini lecture 1 Cryptography Symmetric key cryptography (secret key crypto): sender and receiver keys identical Asymmetric key cryptography (public key crypto): encryption key public, decryption

More information

Part VI. Public-key cryptography

Part VI. Public-key cryptography Part VI Public-key cryptography Drawbacks with symmetric-key cryptography Symmetric-key cryptography: Communicating parties a priori share some secret information. Secure Channel Alice Unsecured Channel

More information

ECEN 5022 Cryptography

ECEN 5022 Cryptography Introduction University of Colorado Spring 2008 Historically, cryptography is the science and study of secret writing (Greek: kryptos = hidden, graphein = to write). Modern cryptography also includes such

More information

UNIT - IV Cryptographic Hash Function 31.1

UNIT - IV Cryptographic Hash Function 31.1 UNIT - IV Cryptographic Hash Function 31.1 31-11 SECURITY SERVICES Network security can provide five services. Four of these services are related to the message exchanged using the network. The fifth service

More information

CS408 Cryptography & Internet Security

CS408 Cryptography & Internet Security CS408 Cryptography & Internet Security Lecture 18: Cryptographic hash functions, Message authentication codes Functions Definition Given two sets, X and Y, a function f : X Y (from set X to set Y), is

More information

Spring 2010: CS419 Computer Security

Spring 2010: CS419 Computer Security Spring 2010: CS419 Computer Security Vinod Ganapathy Lecture 7 Topic: Key exchange protocols Material: Class handout (lecture7_handout.pdf) Chapter 2 in Anderson's book. Today s agenda Key exchange basics

More information

I.D. NUMBER SURNAME OTHER NAMES

I.D. NUMBER SURNAME OTHER NAMES THE UNIVERSITY OF CALGARY DEPARTMENT OF COMPUTER SCIENCE DEPARTMENT OF MATHEMATICS AND STATISTICS FINAL EXAMINATION SOLUTION KEY CPSC/PMAT 418 L01 Introduction to Cryptography Fall 2017 December 19, 2017,

More information

ISA 662 Internet Security Protocols. Outline. Prime Numbers (I) Beauty of Mathematics. Division (II) Division (I)

ISA 662 Internet Security Protocols. Outline. Prime Numbers (I) Beauty of Mathematics. Division (II) Division (I) Outline ISA 662 Internet Security Protocols Some Math Essentials & History Asymmetric signatures and key exchange Asymmetric encryption Symmetric MACs Lecture 2 ISA 662 1 2 Beauty of Mathematics Demonstration

More information

Other Uses of Cryptography. Cryptography Goals. Basic Problem and Terminology. Other Uses of Cryptography. What Can Go Wrong? Why Do We Need a Key?

Other Uses of Cryptography. Cryptography Goals. Basic Problem and Terminology. Other Uses of Cryptography. What Can Go Wrong? Why Do We Need a Key? ryptography Goals Protect private communication in the public world and are shouting messages over a crowded room no one can understand what they are saying 1 Other Uses of ryptography Authentication should

More information

Computer Security. 08r. Pre-exam 2 Last-minute Review Cryptography. Paul Krzyzanowski. Rutgers University. Spring 2018

Computer Security. 08r. Pre-exam 2 Last-minute Review Cryptography. Paul Krzyzanowski. Rutgers University. Spring 2018 Computer Security 08r. Pre-exam 2 Last-minute Review Cryptography Paul Krzyzanowski Rutgers University Spring 2018 March 26, 2018 CS 419 2018 Paul Krzyzanowski 1 Cryptographic Systems March 26, 2018 CS

More information

ECE 646 Fall 2009 Final Exam December 15, Multiple-choice test

ECE 646 Fall 2009 Final Exam December 15, Multiple-choice test ECE 646 Fall 2009 Final Exam December 15, 2009 Multiple-choice test 1. (1 pt) Parallel processing can be used to speed up the following cryptographic transformations (please note that multiple answers

More information

Public-key encipherment concept

Public-key encipherment concept Date: onday, October 21, 2002 Prof.: Dr Jean-Yves Chouinard Design of Secure Computer Systems CSI4138/CEG4394 Notes on Public Key Cryptography Public-key encipherment concept Each user in a secure communication

More information

CS 470 Spring Security. Mike Lam, Professor. a.k.a. Why on earth do Alice and Bob need to share so many secrets?!?

CS 470 Spring Security. Mike Lam, Professor. a.k.a. Why on earth do Alice and Bob need to share so many secrets?!? 50fb6be35f4c3105 9d4ed08fb86d8887 b746c452a9c9443b 15b22f450c76218e CS 470 Spring 2018 9df7031cdbff9d10 b700a92855f16328 5b757e66d2131841 62fedd7d9131e42e Mike Lam, Professor Security a.k.a. Why on earth

More information

Homework 1 CS161 Computer Security, Spring 2008 Assigned 2/4/08 Due 2/13/08

Homework 1 CS161 Computer Security, Spring 2008 Assigned 2/4/08 Due 2/13/08 Homework 1 CS161 Computer Security, Spring 2008 Assigned 2/4/08 Due 2/13/08 This homework assignment is due Wednesday, February 13 at the beginning of lecture. Please bring a hard copy to class; either

More information

Outline. Data Encryption Standard. Symmetric-Key Algorithms. Lecture 4

Outline. Data Encryption Standard. Symmetric-Key Algorithms. Lecture 4 EEC 693/793 Special Topics in Electrical Engineering Secure and Dependable Computing Lecture 4 Department of Electrical and Computer Engineering Cleveland State University wenbing@ieee.org Outline Review

More information

Dr. Jinyuan (Stella) Sun Dept. of Electrical Engineering and Computer Science University of Tennessee Fall 2010

Dr. Jinyuan (Stella) Sun Dept. of Electrical Engineering and Computer Science University of Tennessee Fall 2010 Dr. Jinyuan (Stella) Sun Dept. of Electrical Engineering and Computer Science University of Tennessee Fall 2010 1 Photuris and SKIP PHASE 1 IKE PHASE 2 IKE How is SA established? How do parties negotiate

More information

CRYPTOGRAPHY AND NETWROK SECURITY-QUESTION BANK

CRYPTOGRAPHY AND NETWROK SECURITY-QUESTION BANK CRYPTOGRAPHY AND NETWROK SECURITY-QUESTION BANK UNIT-1 1. Answer the following: a. What is Non-repudiation b. Distinguish between stream and block ciphers c. List out the problems of one time pad d. Define

More information

How many DES keys, on the average, encrypt a particular plaintext block to a particular ciphertext block?

How many DES keys, on the average, encrypt a particular plaintext block to a particular ciphertext block? Homework 1. Come up with as efficient an encoding as you can to specify a completely general one-to-one mapping between 64-bit input values and 64-bit output values. 2. Token cards display a number that

More information

Chapter 3 Public Key Cryptography

Chapter 3 Public Key Cryptography Cryptography and Network Security Chapter 3 Public Key Cryptography Lectured by Nguyễn Đức Thái Outline Number theory overview Public key cryptography RSA algorithm 2 Prime Numbers A prime number is an

More information

Network Security. Chapter 4 Public Key Cryptography. Public Key Cryptography (4) Public Key Cryptography

Network Security. Chapter 4 Public Key Cryptography. Public Key Cryptography (4) Public Key Cryptography Chair for Network Architectures and Services Department of Informatics TU München Prof. Carle Encryption/Decryption using Public Key Cryptography Network Security Chapter 4 Public Key Cryptography However,

More information

LECTURE NOTES ON PUBLIC- KEY CRYPTOGRAPHY. (One-Way Functions and ElGamal System)

LECTURE NOTES ON PUBLIC- KEY CRYPTOGRAPHY. (One-Way Functions and ElGamal System) Department of Software The University of Babylon LECTURE NOTES ON PUBLIC- KEY CRYPTOGRAPHY (One-Way Functions and ElGamal System) By College of Information Technology, University of Babylon, Iraq Samaher@itnet.uobabylon.edu.iq

More information

ICT 6541 Applied Cryptography Lecture 8 Entity Authentication/Identification

ICT 6541 Applied Cryptography Lecture 8 Entity Authentication/Identification ICT 6541 Applied Cryptography Lecture 8 Entity Authentication/Identification Hossen Asiful Mustafa Introduction Entity Authentication is a technique designed to let one party prove the identity of another

More information

Public Key Cryptography

Public Key Cryptography graphy CSS322: Security and Cryptography Sirindhorn International Institute of Technology Thammasat University Prepared by Steven Gordon on 29 December 2011 CSS322Y11S2L07, Steve/Courses/2011/S2/CSS322/Lectures/rsa.tex,

More information

Ideal Security Protocol. Identify Friend or Foe (IFF) MIG in the Middle 4/2/2012

Ideal Security Protocol. Identify Friend or Foe (IFF) MIG in the Middle 4/2/2012 Ideal Security Protocol Satisfies security requirements Requirements must be precise Efficient Small computational requirement Small bandwidth usage, network delays Not fragile Works when attacker tries

More information

Understanding Cryptography A Textbook for Students and Practitioners by Christof Paar and Jan Pelzl. Chapter 6 Introduction to Public-Key Cryptography

Understanding Cryptography A Textbook for Students and Practitioners by Christof Paar and Jan Pelzl. Chapter 6 Introduction to Public-Key Cryptography Understanding Cryptography A Textbook for Students and Practitioners by Christof Paar and Jan Pelzl www.crypto-textbook.com Chapter 6 Introduction to Public-Key Cryptography ver. November 18, 2010 These

More information

ASYMMETRIC CRYPTOGRAPHY

ASYMMETRIC CRYPTOGRAPHY ASYMMETRIC CRYPTOGRAPHY CONTENT: 1. Number Theory 2. One Way Function 3. Hash Function 4. Digital Signature 5. RSA (Rivest-Shamir Adleman) References: 1. Applied Cryptography, Bruce Schneier 2. Cryptography

More information

Lecture IV : Cryptography, Fundamentals

Lecture IV : Cryptography, Fundamentals Lecture IV : Cryptography, Fundamentals Internet Security: Principles & Practices John K. Zao, PhD (Harvard) SMIEEE Computer Science Department, National Chiao Tung University Spring 2012 Basic Principles

More information

Test 2 Review. (b) Give one significant advantage of a nonce over a timestamp.

Test 2 Review. (b) Give one significant advantage of a nonce over a timestamp. Test 2 Review Name Student ID number Notation: {X} Bob Apply Bob s public key to X [Y ] Bob Apply Bob s private key to Y E(P, K) Encrypt P with symmetric key K D(C, K) Decrypt C with symmetric key K h(x)

More information

Lecture 5. Cryptographic Hash Functions. Read: Chapter 5 in KPS

Lecture 5. Cryptographic Hash Functions. Read: Chapter 5 in KPS Lecture 5 Cryptographic Hash Functions Read: Chapter 5 in KPS 1 Purpose CHF one of the most important tools in modern cryptography and security CHF-s are used for many authentication, integrity, digital

More information

1. Out of the 3 types of attacks an adversary can mount on a cryptographic algorithm, which ones does differential cryptanalysis utilize?

1. Out of the 3 types of attacks an adversary can mount on a cryptographic algorithm, which ones does differential cryptanalysis utilize? Introduction Answer the following questions. When a word count restriction is given for a question, exceeding it will result in marks being deducted. If your answer is more than twice the maximum length,

More information