CSC474/574 - Information Systems Security: Homework1 Solutions Sketch
|
|
|
- Abel Sanders
- 8 years ago
- Views:
Transcription
1 CSC474/574 - Information Systems Security: Homework1 Solutions Sketch February 20, Consider slide 12 in the handout for topic 2.2. Prove that the decryption process of a one-round Feistel cipher is the same as the input of the corresponding encryption process. That is, (L 2, R 2 ) = (L 0, R 0 ). Ans. R 0 = L 1 = R 2 = R 0 = L 1 = R 2 L 2 = R 1 = L 0 (R 0, K 1 ) = L 2 (R 2, K 1 ) = R 1 (R 0, K 1 ) = L 0 2. Random J. Protocol-esigner has been told to design a scheme to prevent messages from being modified by an intruder. Random J. decides to append to each message a hash of that message. Why doesn t this solve the problem? Ans. Anybody can generate and append a hash to any message. A malicious adversary can easily modify the message and append the recomputed hash value. This modification goes undetected at the receiving end. 3. How many S keys, on the average, encrypt a particular plaintext block to a particular ciphertext block? Ans. There are 2 56 possible keys and 2 64 possible ciphertext blocks for a particular plaintext block. So only about = 1/256 of the possible ciphertext blocks can be obtained with a S key. 4. Alice developed a message authentication code (MAC) based on S. Her algorithm works as follows: For a given input message M, represent M as M = (X 1 X 2... X m ), where X i is a 64-bit block and represents concatenation. Compute elta(m) = X 1 X 2... X m, where represents bit-wise XOR. Then the MAC for M is computed as C K (M) = K (elta(m)), where is S encryption algorithm and 1
2 K is the secret key. Unfortunately, this scheme is vulnerable. escribe an attack against it. Ans. A possible attack on this scheme could be a word reordering attack. A reordering attack is possible because it yields the same hash as the original message. An intruder can easily create a message M and compute W = elta(m) elta(m ) where elta(m W) = elta(m). 5. Let s assume that someone does triple encryption by using with CBC on the inside. Suppose an attacker modifies bit x of ciphertext block n. How does this affect the decrypted plaintext? (See Figure 4-16 and related text for triple S with CBC on the inside. But note that the question is about triple S with CBC on the inside) Ans. Triple encryption using with CBC on the inside is three successive CBC encryptions: ecryption is the inverse operation: m 1 m 2 m 3 m 4 m 5 m 6 IV encrypt with secret key K 1 encrypt with secret key K 2 encrypt with secret key K 3 c 1 c 2 c 3 c 4 c 5 c 6 2
3 m 1 m 2 m 3 m 4 m 5 m 6 IV decrypt with secret key K 1 decrypt with secret key K 2 decrypt with secret key K 3 c 1 c 2 c 3 c 4 c 5 c 6 From this it can be seen that a modification to ciphertext block n propagates to plaintext blocks n through n + 3. No other plaintext blocks are affected. 6. How do you decrypt the encryption specified in Mixing In the plaintext? Ans. The decryption process proceeds as follows: b n = M(K AB c n 1) b n 1 = M(K AB c n 2 )... b n i = M(K AB c n i 1 )... b 2 = M(K AB c 1 ) b 1 = M(K AB IV ) p n = c n b n p n 1 = c n 1 b n 1... p 1 = c 1 b 1 In short, knowing KAB, c i and IV, b i can be generated. Then it is 3
4 easy to compute p i = c i b i 7. A and B want to establish a secure communication channel between them. They do not care about the confidentiality of the messages being transmitted, but they do want to ensure the integrity and authenticity of the messages. Answer the following questions by drawing diagrams that show the procedures of sending and receiving messages. Assume A and B share a common key K. (a) How can they achieve their goal only with secret key cryptography? Ans. Sender Recipient : M K (M) (b) How can they achieve their goal only with hash function (e.g., M5)? Ans. Sender Recipient : {M K (H(M))} (c) Can they get non-repudiation? (2 points) If yes, how? If no, why? Ans. No, it is not possible to achieve non-repudiation with the help of just a commonly shared key because a sender can repudiate a previously authenticated message by claiming that the shared secret was somehow compromised. It is also possible that the recipient who has a copy of the shared secret key might have forged the signature. (d) escribe a way A and B can get non-repudiation. xplain your assumption and draw a diagram to show the procedure. Ans. Using digital signatures 8. The SA algorithm requires a random number each time a digital signature is generated. emonstrate that the SA algorithm is vulnerable if this random number is used twice. Ans. If k 1 = k 2, then r 1 = r 2 and s 1 = [k 1 (H(M 1 )+xr)] mod q and s2 = [k 1 (H(M 2 )+xr)] mod q. Then k = (s1 s2) 1 [H(M 1 )H(M 2 )] mod q. So the private key x can be obtained from s 1 or s 2 above. 9. Manually complete the following operations. xplain your reason for each step. (a) mod mod 17 = 1 4
5 since 17 is a prime and gcd(1234, 17) = 1 we can use Fermat theorem. (b) mod mod 17 = (54 mod 17) (51 mod 16) mod 17 = 3 3 mod 17 = 10 since 17 is a prime and gcd(54, 17) = 1 and φ(17) = 16 (c) mod 51 (d) gcd(33, 121) mod 51 = (53 mod 51) (97 mod φ(51)) mod 51 = 2 (97mod(17)φ(3)) mod 51 = 2 (97 mod 32) mod 51 = 2 1 mod 51 = 2 gcd(33, 121) = gcd(121, 33) = gcd(33, 22) = gcd(22, 11) (e) 2 1 mod 17 = gcd(11, 0) = mod 17 = 8 mod 17 = 9 using the extended uclid algorithm, Y 3 = 1 = gcd(2, 17) and Y 2 = 8 = 2 1 mod 17 (f) log 2,5 (4) since: log 2,5 (4) = mod 5 = mod 5 = mod 5 = mod 5 = mod 5 = 1 Another method is to solve for x from 2 x mod 5 4 mod 5 22 mod 5 x = 2 5
6 10. Consider the polynomial x p 1 = 1( mod p), where p is a prime number. It has at most p 1 roots (because it is a polynomial of degree p 1). Show exactly the roots of this polynomial using Fermat Theorem. Ans. Roots of x p 1 = 1( mod p) = {1, 2, 3,..., p 2, p 1}. According to Fermat theorem, x p 1 = 1( mod p) for all x such that gcd(x, p) = 1, and since p is prime, 1 x p 1 are relative primes to p. 11. Assume that p is a prime number and a is a positive integer not divisible by p. Prove that {a mod p, 2a mod p,...,(p 1)a mod p} = {1, 2,...,(p 1)}. Ans. Assume {a mod p, 2a mod p,...,(p 1)a mod p} {1, 2,...,(p 1)}. Then there exists x and y in {1, 2,...,(p 1)} such that x y and xa ya( mod p). i.e., xa = ya + kp and can be rewritten as (x y)a = kp. Factoring left side yields p m pm k k = kp Then since a is not divisible by p, p is not on the left side which contradicts that p is on the right side. So we can prove that {a mod p, 2a mod p,...,(p 1)a mod p} = {1, 2,...,(p 1)}. 6
Outline. Computer Science 418. Digital Signatures: Observations. Digital Signatures: Definition. Definition 1 (Digital signature) Digital Signatures
Outline Computer Science 418 Digital Signatures Mike Jacobson Department of Computer Science University of Calgary Week 12 1 Digital Signatures 2 Signatures via Public Key Cryptosystems 3 Provable 4 Mike
Cryptographic hash functions and MACs Solved Exercises for Cryptographic Hash Functions and MACs
Cryptographic hash functions and MACs Solved Exercises for Cryptographic Hash Functions and MACs Enes Pasalic University of Primorska Koper, 2014 Contents 1 Preface 3 2 Problems 4 2 1 Preface This is a
Network Security. Computer Networking Lecture 08. March 19, 2012. HKU SPACE Community College. HKU SPACE CC CN Lecture 08 1/23
Network Security Computer Networking Lecture 08 HKU SPACE Community College March 19, 2012 HKU SPACE CC CN Lecture 08 1/23 Outline Introduction Cryptography Algorithms Secret Key Algorithm Message Digest
159.334 Computer Networks. Network Security 1. Professor Richard Harris School of Engineering and Advanced Technology
Network Security 1 Professor Richard Harris School of Engineering and Advanced Technology Presentation Outline Overview of Identification and Authentication The importance of identification and Authentication
CSCE 465 Computer & Network Security
CSCE 465 Computer & Network Security Instructor: Dr. Guofei Gu http://courses.cse.tamu.edu/guofei/csce465/ Public Key Cryptogrophy 1 Roadmap Introduction RSA Diffie-Hellman Key Exchange Public key and
CIS 6930 Emerging Topics in Network Security. Topic 2. Network Security Primitives
CIS 6930 Emerging Topics in Network Security Topic 2. Network Security Primitives 1 Outline Absolute basics Encryption/Decryption; Digital signatures; D-H key exchange; Hash functions; Application of hash
Digital Signature. Raj Jain. Washington University in St. Louis
Digital Signature Raj Jain Washington University in Saint Louis Saint Louis, MO 63130 Jain@cse.wustl.edu Audio/Video recordings of this lecture are available at: http://www.cse.wustl.edu/~jain/cse571-11/
Outline. CSc 466/566. Computer Security. 8 : Cryptography Digital Signatures. Digital Signatures. Digital Signatures... Christian Collberg
Outline CSc 466/566 Computer Security 8 : Cryptography Digital Signatures Version: 2012/02/27 16:07:05 Department of Computer Science University of Arizona collberg@gmail.com Copyright c 2012 Christian
Overview of Public-Key Cryptography
CS 361S Overview of Public-Key Cryptography Vitaly Shmatikov slide 1 Reading Assignment Kaufman 6.1-6 slide 2 Public-Key Cryptography public key public key? private key Alice Bob Given: Everybody knows
CS 758: Cryptography / Network Security
CS 758: Cryptography / Network Security offered in the Fall Semester, 2003, by Doug Stinson my office: DC 3122 my email address: dstinson@uwaterloo.ca my web page: http://cacr.math.uwaterloo.ca/~dstinson/index.html
Client Server Registration Protocol
Client Server Registration Protocol The Client-Server protocol involves these following steps: 1. Login 2. Discovery phase User (Alice or Bob) has K s Server (S) has hash[pw A ].The passwords hashes are
Network Security. Abusayeed Saifullah. CS 5600 Computer Networks. These slides are adapted from Kurose and Ross 8-1
Network Security Abusayeed Saifullah CS 5600 Computer Networks These slides are adapted from Kurose and Ross 8-1 Public Key Cryptography symmetric key crypto v requires sender, receiver know shared secret
Network Security. HIT Shimrit Tzur-David
Network Security HIT Shimrit Tzur-David 1 Goals: 2 Network Security Understand principles of network security: cryptography and its many uses beyond confidentiality authentication message integrity key
Message Authentication Codes. Lecture Outline
Message Authentication Codes Murat Kantarcioglu Based on Prof. Ninghui Li s Slides Message Authentication Code Lecture Outline 1 Limitation of Using Hash Functions for Authentication Require an authentic
Digital Signatures. Murat Kantarcioglu. Based on Prof. Li s Slides. Digital Signatures: The Problem
Digital Signatures Murat Kantarcioglu Based on Prof. Li s Slides Digital Signatures: The Problem Consider the real-life example where a person pays by credit card and signs a bill; the seller verifies
Final Exam. IT 4823 Information Security Administration. Rescheduling Final Exams. Kerberos. Idea. Ticket
IT 4823 Information Security Administration Public Key Encryption Revisited April 5 Notice: This session is being recorded. Lecture slides prepared by Dr Lawrie Brown for Computer Security: Principles
Computer Security: Principles and Practice
Computer Security: Principles and Practice Chapter 20 Public-Key Cryptography and Message Authentication First Edition by William Stallings and Lawrie Brown Lecture slides by Lawrie Brown Public-Key Cryptography
Security. Contents. S-72.3240 Wireless Personal, Local, Metropolitan, and Wide Area Networks 1
Contents Security requirements Public key cryptography Key agreement/transport schemes Man-in-the-middle attack vulnerability Encryption. digital signature, hash, certification Complete security solutions
RSA Attacks. By Abdulaziz Alrasheed and Fatima
RSA Attacks By Abdulaziz Alrasheed and Fatima 1 Introduction Invented by Ron Rivest, Adi Shamir, and Len Adleman [1], the RSA cryptosystem was first revealed in the August 1977 issue of Scientific American.
Elements of Applied Cryptography Public key encryption
Network Security Elements of Applied Cryptography Public key encryption Public key cryptosystem RSA and the factorization problem RSA in practice Other asymmetric ciphers Asymmetric Encryption Scheme Let
Introduction to Cryptography CS 355
Introduction to Cryptography CS 355 Lecture 30 Digital Signatures CS 355 Fall 2005 / Lecture 30 1 Announcements Wednesday s lecture cancelled Friday will be guest lecture by Prof. Cristina Nita- Rotaru
Cryptography: Authentication, Blind Signatures, and Digital Cash
Cryptography: Authentication, Blind Signatures, and Digital Cash Rebecca Bellovin 1 Introduction One of the most exciting ideas in cryptography in the past few decades, with the widest array of applications,
Network Security. Gaurav Naik Gus Anderson. College of Engineering. Drexel University, Philadelphia, PA. Drexel University. College of Engineering
Network Security Gaurav Naik Gus Anderson, Philadelphia, PA Lectures on Network Security Feb 12 (Today!): Public Key Crypto, Hash Functions, Digital Signatures, and the Public Key Infrastructure Feb 14:
1 Message Authentication
Theoretical Foundations of Cryptography Lecture Georgia Tech, Spring 200 Message Authentication Message Authentication Instructor: Chris Peikert Scribe: Daniel Dadush We start with some simple questions
Notes on Network Security Prof. Hemant K. Soni
Chapter 9 Public Key Cryptography and RSA Private-Key Cryptography traditional private/secret/single key cryptography uses one key shared by both sender and receiver if this key is disclosed communications
Advanced Cryptography
Family Name:... First Name:... Section:... Advanced Cryptography Final Exam July 18 th, 2006 Start at 9:15, End at 12:00 This document consists of 12 pages. Instructions Electronic devices are not allowed.
Public Key Cryptography: RSA and Lots of Number Theory
Public Key Cryptography: RSA and Lots of Number Theory Public vs. Private-Key Cryptography We have just discussed traditional symmetric cryptography: Uses a single key shared between sender and receiver
Introduction to Computer Security
Introduction to Computer Security Hash Functions and Digital Signatures Pavel Laskov Wilhelm Schickard Institute for Computer Science Integrity objective in a wide sense Reliability Transmission errors
Network Security Technology Network Management
COMPUTER NETWORKS Network Security Technology Network Management Source Encryption E(K,P) Decryption D(K,C) Destination The author of these slides is Dr. Mark Pullen of George Mason University. Permission
Authentication requirement Authentication function MAC Hash function Security of
UNIT 3 AUTHENTICATION Authentication requirement Authentication function MAC Hash function Security of hash function and MAC SHA HMAC CMAC Digital signature and authentication protocols DSS Slides Courtesy
Network Security CS 5490/6490 Fall 2015 Lecture Notes 8/26/2015
Network Security CS 5490/6490 Fall 2015 Lecture Notes 8/26/2015 Chapter 2: Introduction to Cryptography What is cryptography? It is a process/art of mangling information in such a way so as to make it
Practice Questions. CS161 Computer Security, Fall 2008
Practice Questions CS161 Computer Security, Fall 2008 Name Email address Score % / 100 % Please do not forget to fill up your name, email in the box in the midterm exam you can skip this here. These practice
6.857 Computer and Network Security Fall Term, 1997 Lecture 4 : 16 September 1997 Lecturer: Ron Rivest Scribe: Michelle Goldberg 1 Conditionally Secure Cryptography Conditionally (or computationally) secure
Overview of Cryptographic Tools for Data Security. Murat Kantarcioglu
UT DALLAS Erik Jonsson School of Engineering & Computer Science Overview of Cryptographic Tools for Data Security Murat Kantarcioglu Pag. 1 Purdue University Cryptographic Primitives We will discuss the
Message Authentication Codes
2 MAC Message Authentication Codes : and Cryptography Sirindhorn International Institute of Technology Thammasat University Prepared by Steven Gordon on 28 October 2013 css322y13s2l08, Steve/Courses/2013/s2/css322/lectures/mac.tex,
Computer Networks. Network Security and Ethics. Week 14. College of Information Science and Engineering Ritsumeikan University
Computer Networks Network Security and Ethics Week 14 College of Information Science and Engineering Ritsumeikan University Security Intro for Admins l Network administrators can break security into two
SECURITY IN NETWORKS
SECURITY IN NETWORKS GOALS Understand principles of network security: Cryptography and its many uses beyond confidentiality Authentication Message integrity Security in practice: Security in application,
Network Security. Abusayeed Saifullah. CS 5600 Computer Networks. These slides are adapted from Kurose and Ross 8-1
Network Security Abusayeed Saifullah CS 5600 Computer Networks These slides are adapted from Kurose and Ross 8-1 Goals v understand principles of network security: cryptography and its many uses beyond
Chapter 7: Network security
Chapter 7: Network security Foundations: what is security? cryptography authentication message integrity key distribution and certification Security in practice: application layer: secure e-mail transport
CRYPTOGRAPHY IN NETWORK SECURITY
ELE548 Research Essays CRYPTOGRAPHY IN NETWORK SECURITY AUTHOR: SHENGLI LI INSTRUCTOR: DR. JIEN-CHUNG LO Date: March 5, 1999 Computer network brings lots of great benefits and convenience to us. We can
Principles of Network Security
he Network Security Model Bob and lice want to communicate securely. rudy (the adversary) has access to the channel. lice channel data, control s Bob Kai Shen data secure sender secure receiver data rudy
Network Security (2) CPSC 441 Department of Computer Science University of Calgary
Network Security (2) CPSC 441 Department of Computer Science University of Calgary 1 Friends and enemies: Alice, Bob, Trudy well-known in network security world Bob, Alice (lovers!) want to communicate
Network Security. Security Attacks. Normal flow: Interruption: 孫 宏 民 hmsun@cs.nthu.edu.tw Phone: 03-5742968 國 立 清 華 大 學 資 訊 工 程 系 資 訊 安 全 實 驗 室
Network Security 孫 宏 民 hmsun@cs.nthu.edu.tw Phone: 03-5742968 國 立 清 華 大 學 資 訊 工 程 系 資 訊 安 全 實 驗 室 Security Attacks Normal flow: sender receiver Interruption: Information source Information destination
Message Authentication Code
Message Authentication Code Ali El Kaafarani Mathematical Institute Oxford University 1 of 44 Outline 1 CBC-MAC 2 Authenticated Encryption 3 Padding Oracle Attacks 4 Information Theoretic MACs 2 of 44
Public Key Cryptography Overview
Ch.20 Public-Key Cryptography and Message Authentication I will talk about it later in this class Final: Wen (5/13) 1630-1830 HOLM 248» give you a sample exam» Mostly similar to homeworks» no electronic
EXAM questions for the course TTM4135 - Information Security May 2013. Part 1
EXAM questions for the course TTM4135 - Information Security May 2013 Part 1 This part consists of 5 questions all from one common topic. The number of maximal points for every correctly answered question
Cryptography and Network Security Chapter 9
Cryptography and Network Security Chapter 9 Fifth Edition by William Stallings Lecture slides by Lawrie Brown (with edits by RHB) Chapter 9 Public Key Cryptography and RSA Every Egyptian received two names,
Lecture 9 - Message Authentication Codes
Lecture 9 - Message Authentication Codes Boaz Barak March 1, 2010 Reading: Boneh-Shoup chapter 6, Sections 9.1 9.3. Data integrity Until now we ve only been interested in protecting secrecy of data. However,
Cryptography and Network Security Prof. D. Mukhopadhyay Department of Computer Science and Engineering Indian Institute of Technology, Kharagpur
Cryptography and Network Security Prof. D. Mukhopadhyay Department of Computer Science and Engineering Indian Institute of Technology, Kharagpur Module No. # 01 Lecture No. # 02 Overview on Modern Cryptography
The application of prime numbers to RSA encryption
The application of prime numbers to RSA encryption Prime number definition: Let us begin with the definition of a prime number p The number p, which is a member of the set of natural numbers N, is considered
Network Security. Security. Security Services. Crytographic algorithms. privacy authenticity Message integrity. Public key (RSA) Message digest (MD5)
Network Security Security Crytographic algorithms Security Services Secret key (DES) Public key (RSA) Message digest (MD5) privacy authenticity Message integrity Secret Key Encryption Plain text Plain
RSA and Primality Testing
and Primality Testing Joan Boyar, IMADA, University of Southern Denmark Studieretningsprojekter 2010 1 / 81 Correctness of cryptography cryptography Introduction to number theory Correctness of with 2
CS 348: Computer Networks. - Security; 30 th - 31 st Oct 2012. Instructor: Sridhar Iyer IIT Bombay
CS 348: Computer Networks - Security; 30 th - 31 st Oct 2012 Instructor: Sridhar Iyer IIT Bombay Network security Security Plan (RFC 2196) Identify assets Determine threats Perform risk analysis Implement
MACs Message authentication and integrity. Table of contents
MACs Message authentication and integrity Foundations of Cryptography Computer Science Department Wellesley College Table of contents Introduction MACs Constructing Secure MACs Secure communication and
CS3235 - Computer Security Third topic: Crypto Support Sys
Systems used with cryptography CS3235 - Computer Security Third topic: Crypto Support Systems National University of Singapore School of Computing (Some slides drawn from Lawrie Brown s, with permission)
QUANTUM COMPUTERS AND CRYPTOGRAPHY. Mark Zhandry Stanford University
QUANTUM COMPUTERS AND CRYPTOGRAPHY Mark Zhandry Stanford University Classical Encryption pk m c = E(pk,m) sk m = D(sk,c) m??? Quantum Computing Attack pk m aka Post-quantum Crypto c = E(pk,m) sk m = D(sk,c)
Secure Network Communication Part II II Public Key Cryptography. Public Key Cryptography
Kommunikationssysteme (KSy) - Block 8 Secure Network Communication Part II II Public Key Cryptography Dr. Andreas Steffen 2000-2001 A. Steffen, 28.03.2001, KSy_RSA.ppt 1 Secure Key Distribution Problem
Public Key Cryptography and RSA. Review: Number Theory Basics
Public Key Cryptography and RSA Murat Kantarcioglu Based on Prof. Ninghui Li s Slides Review: Number Theory Basics Definition An integer n > 1 is called a prime number if its positive divisors are 1 and
Authentication, digital signatures, PRNG
Multimedia Security Authentication, digital signatures, PRNG Mauro Barni University of Siena Beyond confidentiality Up to now, we have been concerned with protecting message content (i.e. confidentiality)
Application Layer (1)
Application Layer (1) Functionality: providing applications (e-mail, www, USENET etc) providing support protocols to allow the real applications to function properly security comprising a large number
Principles of Public Key Cryptography. Applications of Public Key Cryptography. Security in Public Key Algorithms
Principles of Public Key Cryptography Chapter : Security Techniques Background Secret Key Cryptography Public Key Cryptography Hash Functions Authentication Chapter : Security on Network and Transport
Cryptography and Network Security Prof. D. Mukhopadhyay Department of Computer Science and Engineering Indian Institute of Technology, Kharagpur
Cryptography and Network Security Prof. D. Mukhopadhyay Department of Computer Science and Engineering Indian Institute of Technology, Kharagpur Lecture No. # 11 Block Cipher Standards (DES) (Refer Slide
Schnorr Signcryption. Combining public key encryption with Schnorr digital signature. Laura Savu, University of Bucharest, Romania
Schnorr Signcryption Combining public key encryption with Schnorr digital signature Laura Savu, University of Bucharest, Romania IT Security for the Next Generation European Cup, Prague 17-19 February,
Cryptosystems. Bob wants to send a message M to Alice. Symmetric ciphers: Bob and Alice both share a secret key, K.
Cryptosystems Bob wants to send a message M to Alice. Symmetric ciphers: Bob and Alice both share a secret key, K. C= E(M, K), Bob sends C Alice receives C, M=D(C,K) Use the same key to decrypt. Public
Cryptographic Hash Functions Message Authentication Digital Signatures
Cryptographic Hash Functions Message Authentication Digital Signatures Abstract We will discuss Cryptographic hash functions Message authentication codes HMAC and CBC-MAC Digital signatures 2 Encryption/Decryption
Information Security
Information Security Dr. Vedat Coşkun Malardalen September 15th, 2009 08:00 10:00 vedatcoskun@isikun.edu.tr www.isikun.edu.tr/~vedatcoskun What needs to be secured? With the rapid advances in networked
Cryptography & Network Security. Introduction. Chester Rebeiro IIT Madras
Cryptography & Network Security Introduction Chester Rebeiro IIT Madras The Connected World 2 Information Storage 3 Increased Security Breaches 81% more in 2015 http://www.pwc.co.uk/assets/pdf/2015-isbs-executive-summary-02.pdf
Digital Signatures. (Note that authentication of sender is also achieved by MACs.) Scan your handwritten signature and append it to the document?
Cryptography Digital Signatures Professor: Marius Zimand Digital signatures are meant to realize authentication of the sender nonrepudiation (Note that authentication of sender is also achieved by MACs.)
Lecture 10: CPA Encryption, MACs, Hash Functions. 2 Recap of last lecture - PRGs for one time pads
CS 7880 Graduate Cryptography October 15, 2015 Lecture 10: CPA Encryption, MACs, Hash Functions Lecturer: Daniel Wichs Scribe: Matthew Dippel 1 Topic Covered Chosen plaintext attack model of security MACs
12/3/08. Security in Wireless LANs and Mobile Networks. Wireless Magnifies Exposure Vulnerability. Mobility Makes it Difficult to Establish Trust
Security in Wireless LANs and Mobile Networks Wireless Magnifies Exposure Vulnerability Information going across the wireless link is exposed to anyone within radio range RF may extend beyond a room or
Public Key (asymmetric) Cryptography
Public-Key Cryptography UNIVERSITA DEGLI STUDI DI PARMA Dipartimento di Ingegneria dell Informazione Public Key (asymmetric) Cryptography Luca Veltri (mail.to: luca.veltri@unipr.it) Course of Network Security,
Cryptography and Network Security Department of Computer Science and Engineering Indian Institute of Technology Kharagpur
Cryptography and Network Security Department of Computer Science and Engineering Indian Institute of Technology Kharagpur Module No. # 01 Lecture No. # 05 Classic Cryptosystems (Refer Slide Time: 00:42)
Compter Networks Chapter 9: Network Security
Goals of this chapter Compter Networks Chapter 9: Network Security Give a brief glimpse of security in communication networks Basic goals and mechanisms Holger Karl Slide set: Günter Schäfer, TU Ilmenau
Authenticated encryption
Authenticated encryption Dr. Enigma Department of Electrical Engineering & Computer Science University of Central Florida wocjan@eecs.ucf.edu October 16th, 2013 Active attacks on CPA-secure encryption
Module: Applied Cryptography. Professor Patrick McDaniel Fall 2010. CSE543 - Introduction to Computer and Network Security
CSE543 - Introduction to Computer and Network Security Module: Applied Cryptography Professor Patrick McDaniel Fall 2010 Page 1 Key Distribution/Agreement Key Distribution is the process where we assign
Security Sensor Network. Biswajit panja
Security Sensor Network Biswajit panja 1 Topics Security Issues in Wired Network Security Issues in Wireless Network Security Issues in Sensor Network 2 Security Issues in Wired Network 3 Security Attacks
Cryptography and Network Security
Cryptography and Network Security Fifth Edition by William Stallings Chapter 9 Public Key Cryptography and RSA Private-Key Cryptography traditional private/secret/single key cryptography uses one key shared
Overview of Symmetric Encryption
CS 361S Overview of Symmetric Encryption Vitaly Shmatikov Reading Assignment Read Kaufman 2.1-4 and 4.2 slide 2 Basic Problem ----- ----- -----? Given: both parties already know the same secret Goal: send
Content Teaching Academy at James Madison University
Content Teaching Academy at James Madison University 1 2 The Battle Field: Computers, LANs & Internetworks 3 Definitions Computer Security - generic name for the collection of tools designed to protect
The Misuse of RC4 in Microsoft Word and Excel
The Misuse of RC4 in Microsoft Word and Excel Hongjun Wu Institute for Infocomm Research, Singapore hongjun@i2r.a-star.edu.sg Abstract. In this report, we point out a serious security flaw in Microsoft
SFWR ENG 4C03 - Computer Networks & Computer Security
KEY MANAGEMENT SFWR ENG 4C03 - Computer Networks & Computer Security Researcher: Jayesh Patel Student No. 9909040 Revised: April 4, 2005 Introduction Key management deals with the secure generation, distribution,
Lecture Objectives. Lecture 8 Mobile Networks: Security in Wireless LANs and Mobile Networks. Agenda. References
Lecture Objectives Wireless Networks and Mobile Systems Lecture 8 Mobile Networks: Security in Wireless LANs and Mobile Networks Introduce security vulnerabilities and defenses Describe security functions
Software Implementation of Gong-Harn Public-key Cryptosystem and Analysis
Software Implementation of Gong-Harn Public-key Cryptosystem and Analysis by Susana Sin A thesis presented to the University of Waterloo in fulfilment of the thesis requirement for the degree of Master
Cryptography and Network Security Digital Signature
Cryptography and Network Security Digital Signature Xiang-Yang Li Message Authentication Digital Signature Authentication Authentication requirements Authentication functions Mechanisms MAC: message authentication
1 Signatures vs. MACs
CS 120/ E-177: Introduction to Cryptography Salil Vadhan and Alon Rosen Nov. 22, 2006 Lecture Notes 17: Digital Signatures Recommended Reading. Katz-Lindell 10 1 Signatures vs. MACs Digital signatures
Digital signatures. Informal properties
Digital signatures Informal properties Definition. A digital signature is a number dependent on some secret known only to the signer and, additionally, on the content of the message being signed Property.
Cryptography Exercises
Cryptography Exercises 1 Contents 1 source coding 3 2 Caesar Cipher 4 3 Ciphertext-only Attack 5 4 Classification of Cryptosystems-Network Nodes 6 5 Properties of modulo Operation 10 6 Vernam Cipher 11
A Proposal for Authenticated Key Recovery System 1
A Proposal for Authenticated Key Recovery System 1 Tsuyoshi Nishioka a, Kanta Matsuura a, Yuliang Zheng b,c, and Hideki Imai b a Information & Communication Business Div. ADVANCE Co., Ltd. 5-7 Nihombashi
SAMPLE EXAM QUESTIONS MODULE EE5552 NETWORK SECURITY AND ENCRYPTION ECE, SCHOOL OF ENGINEERING AND DESIGN BRUNEL UNIVERSITY UXBRIDGE MIDDLESEX, UK
SAMPLE EXAM QUESTIONS MODULE EE5552 NETWORK SECURITY AND ENCRYPTION September 2010 (reviewed September 2014) ECE, SCHOOL OF ENGINEERING AND DESIGN BRUNEL UNIVERSITY UXBRIDGE MIDDLESEX, UK NETWORK SECURITY
Computer Networks 1 (Mạng Máy Tính 1) Lectured by: Dr. Phạm Trần Vũ MEng. Nguyễn CaoĐạt
Computer Networks 1 (Mạng Máy Tính 1) Lectured by: Dr. Phạm Trần Vũ MEng. Nguyễn CaoĐạt 1 Lecture 11: Network Security Reference: Chapter 8 - Computer Networks, Andrew S. Tanenbaum, 4th Edition, Prentice
Digital Signatures. Prof. Zeph Grunschlag
Digital Signatures Prof. Zeph Grunschlag (Public Key) Digital Signatures PROBLEM: Alice would like to prove to Bob, Carla, David,... that has really sent them a claimed message. E GOAL: Alice signs each
Chapter 8 Security. IC322 Fall 2014. Computer Networking: A Top Down Approach. 6 th edition Jim Kurose, Keith Ross Addison-Wesley March 2012
Chapter 8 Security IC322 Fall 2014 Computer Networking: A Top Down Approach 6 th edition Jim Kurose, Keith Ross Addison-Wesley March 2012 All material copyright 1996-2012 J.F Kurose and K.W. Ross, All
Lecture 3: One-Way Encryption, RSA Example
ICS 180: Introduction to Cryptography April 13, 2004 Lecturer: Stanislaw Jarecki Lecture 3: One-Way Encryption, RSA Example 1 LECTURE SUMMARY We look at a different security property one might require
Cryptography Lecture 8. Digital signatures, hash functions
Cryptography Lecture 8 Digital signatures, hash functions A Message Authentication Code is what you get from symmetric cryptography A MAC is used to prevent Eve from creating a new message and inserting
CIS 5371 Cryptography. 8. Encryption --
CIS 5371 Cryptography p y 8. Encryption -- Asymmetric Techniques Textbook encryption algorithms In this chapter, security (confidentiality) is considered in the following sense: All-or-nothing secrecy.
EXAM questions for the course TTM4135 - Information Security June 2010. Part 1
EXAM questions for the course TTM4135 - Information Security June 2010 Part 1 This part consists of 6 questions all from one common topic. The number of maximal points for every correctly answered question
SECURITY IMPROVMENTS TO THE DIFFIE-HELLMAN SCHEMES
www.arpapress.com/volumes/vol8issue1/ijrras_8_1_10.pdf SECURITY IMPROVMENTS TO THE DIFFIE-HELLMAN SCHEMES Malek Jakob Kakish Amman Arab University, Department of Computer Information Systems, P.O.Box 2234,
Cryptography and Network Security Chapter 12
Cryptography and Network Security Chapter 12 Fifth Edition by William Stallings Lecture slides by Lawrie Brown (with edits by RHB) Chapter 12 Message Authentication Codes At cats' green on the Sunday he
7! Cryptographic Techniques! A Brief Introduction
7! Cryptographic Techniques! A Brief Introduction 7.1! Introduction to Cryptography! 7.2! Symmetric Encryption! 7.3! Asymmetric (Public-Key) Encryption! 7.4! Digital Signatures! 7.5! Public Key Infrastructures
Email: The Electronic Postcard. By Daniel Herren
Email: The Electronic Postcard By Daniel Herren 1 Table of Contents 1.0 Introduction.page 3 2.0 Internet Overview...page 3,4 3.0 Email vulnerabilities...page 5-7 3.1 Privacy..page 5 3.2 Authentication.page