International Data Encryption Algorithm CS-627-1 Fall 2004 By How-Shen Chang Table of Contents: Introduction 2 Description of IDEA 3 Key Generation 3 Encryption 4 Decryption 6 Modes of operation 6 Weak keys for IDEA 6 Implementation 7 Applications 8 Conclusion 9 Introduction The Data Encryption Standard (DES) algorithm has been a popular secret key encryption algorithm and is used in many commercial and financial applications. Although introduced in 1976‚ it
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Exam Name___________________________________ TRUE/FALSE. Write ’T’ if the statement is true and ’F’ if the statement is false. 1) With the introduction of the computer the need for automated tools for protecting files and other information stored on the computer became evident. 2) There is a natural tendency on the part of users and system managers to perceive little benefit from security investment until a security failure occurs. 3) There are clear boundaries between network security and internet
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combination to be stored on disk. From cryptographer Kestas Kuliukas: “A rainbow table chain starts with an arbitrary plaintext‚ hashes it‚ reduces the hash to another plaintext‚ hashes the new plaintext‚ and so on. The table stores only the starting plaintext and the final hash‚ and so a chain "containing" millions of hashes can be represented with only a single starting plaintext‚ and a single finishing hash.” The efficiency of rainbow table is remarkable. It would take 3‚108 terabytes of disk
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two types of operation are performed. (i) Encryption and (ii) Decryption. To encrypt and decrypt data a secret key is used. After encryption original data is converted into another format known as cyphertext‚ which is not easy to understand. Plaintext- Original message that can be understood by anyone. Secret Key- A key that is used to change the format of the original message. Ciphertext- Another format of the original message that cannot be understood by anyone. Steps of Cryptography:(i)
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SOLUTIONS MANUAL CRYPTOGRAPHY AND NETWORK SECURITY PRINCIPLES AND PRACTICE FOURTH EDITION WILLIAM STALLINGS Copyright 2006: William Stallings -2- © 2006 by William Stallings All rights reserved. No part of this document may be reproduced‚ in any form or by any means‚ or posted on the Internet‚ without permission in writing from the author. -3- NOTICE This manual contains solutions to all of the review questions and homework problems in Cryptography and Network Security‚
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detail (10+10 =20 Marks) 2. Explain RC4 algorithm. Encrypt the Message “HI” using RC4 algorithm‚ with four states and 2 bit key values are [2‚5] ASCII value for H – 1001000I – 1001001 (5+5=10 Marks) 3. a. Find the plaintext from the ciphertext using cesar cipher – VSRQJHEREVTXDUHSDQWU b. Encipher “CHUCK NORRIS IS A TOUGH GUY” using a rail fence cipher. c. Decipher “JYENR BOALR ERIIE LOLAR ISNDE TLYRC ACIFB PE” using a simple 4
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Final Exam of Computer Networks (ICE 1230) 2008.5. 27. Answer in English and Total 15 points 1. Why is it said that packet switching employs statistical multiplexing? Contrast statistical multiplexing with the multiplexing that takes place in TDM. (1 point) Answer: In a packet switched network‚ the packets from different sources flowing on a link do not follow any fixed‚ pre-defined pattern. In TDM circuit switching‚ each host gets the same slot in a revolving TDM frame. 2. In BitTorrent
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decipher a text encrypted with the Caesar cipher‚ and why? Floating frequency is the most effective tool used to decipher a text encrypted with the Caesar cipher. Floating frequency replace one letter of the plaintext with another to produce the cypher text‚ and any particular letter in the plaintext will always‚ in the simplest and most easily breakable of these cyphers‚ turn into the same letter in the cypher. For instance‚ all E’s will turn into X’s. Floating frequency is based on the fact that certain
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Chapter 9 1 Identify a security objective that adds value to a business. Confidentiality Privacy Integrity Acess Control Authorization 2 True or False: AES is an asymmetric encryption algorithm. False 3 True or False: 3DES is an asymmetric encryption algorithm. False 4 True or False: RSA is an asymmetric encryption algorithm. True 5 True or False: RC4 is an asymmetric encryption algorithm. False 6 Identify a security principle that can be satisfied with an asymmetric digital signature and not by
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ePayment Security ECOM 6016 Electronic Payment Systems • Keep financial data secret from unauthorized parties (privacy) – CRYPTOGRAPHY Lecture 3 ePayment Security • Verify that messages have not been altered in transit (integrity) – HASH FUNCTIONS • Prove that a party engaged in a transaction ( (nonrepudiation) ) – DIGITAL SIGNATURES • Verify identity of users (authentication) – PASSWORDS‚ DIGITAL CERTIFICATES THE UNIVERSITY OF HONG KONG FEB/MAR 2012 © 2012 MICHAEL I. SHAMOS
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